FlintTable Class Reference

Class managing a Btree table in a Flint database. More...

#include <flint_table.h>

Inheritance diagram for FlintTable:

Collaboration diagram for FlintTable:

List of all members.

Public Member Functions

FlintTable (const char *tablename_, const std::string &path_, bool readonly_, int compress_strategy_=DONT_COMPRESS, bool lazy=false)

Create a new Btree object.

~FlintTable ()

Close the Btree.

void close (bool permanent=false)

Close the Btree.

bool exists () const

Determine whether the btree exists on disk.

void open ()

Open the btree at the latest revision.

bool open (flint_revision_number_t revision_)

Open the btree at a given revision.

void flush_db ()

Flush any outstanding changes to the DB file of the table.

void commit (flint_revision_number_t revision, int changes_fd=-1, const std::string *changes_tail=NULL)

Commit any outstanding changes to the table.

void write_changed_blocks (int changes_fd)

Append the list of blocks changed to a changeset file.

void cancel ()

Cancel any outstanding changes.

bool get_exact_entry (const std::string &key, std::string &tag) const

Read an entry from the table, if and only if it is exactly that being asked for.

bool key_exists (const std::string &key) const

Check if a key exists in the Btree.

bool read_tag (Cursor_ *C_, std::string *tag, bool keep_compressed) const

Read the tag value for the key pointed to by cursor C_.

void add (const std::string &key, std::string tag, bool already_compressed=false)

Add a key/tag pair to the table, replacing any existing pair with the same key.

bool del (const std::string &key)

Delete an entry from the table.

void erase ()

Erase this table from disk.

void set_block_size (unsigned int block_size_)

Set the block size.

unsigned int get_block_size () const

Get the block size.

void create_and_open (unsigned int blocksize)

Create a new empty btree structure on disk and open it at the initial revision.

void set_full_compaction (bool parity)

flint_revision_number_t get_latest_revision_number () const

Get the latest revision number stored in this table.

flint_revision_number_t get_open_revision_number () const

Get the revision number at which this table is currently open.

flint_tablesize_t get_entry_count () const

Return a count of the number of entries in the table.

bool empty () const

Return true if there are no entries in the table.

FlintCursor * cursor_get () const

Get a cursor for reading from the table.

bool is_modified () const

Determine whether the object contains uncommitted modifications.

void set_max_item_size (size_t block_capacity)

Set the maximum item size given the block capacity.

Protected Member Functions

bool do_open_to_read (bool revision_supplied, flint_revision_number_t revision_)

Perform the opening operation to read.

bool do_open_to_write (bool revision_supplied, flint_revision_number_t revision_, bool create_db=false)

Perform the opening operation to write.

bool basic_open (bool revision_supplied, flint_revision_number_t revision)

bool find (Cursor_ *) const

find(C_) searches for the key of B->kt in the B-tree.

int delete_kt ()

void read_block (uint4 n, byte *p) const

read_block(n, p) reads block n of the DB file to address p.

void write_block (uint4 n, const byte *p) const

write_block(n, p) writes block n in the DB file from address p.

XAPIAN_NORETURN (void set_overwritten() const)

void block_to_cursor (Cursor_ *C_, int j, uint4 n) const

void alter ()

Btree::alter(); is called when the B-tree is to be altered.

void compact (byte *p)

compact(p) compact the block at p by shuffling all the items up to the end.

void enter_key (int j, Key_ prevkey, Key_ newkey)

enter_key(j, prevkey, newkey) is called after a block split.

int mid_point (byte *p)

mid_point(p) finds the directory entry in c that determines the approximate mid point of the data in the block at p.

void add_item_to_block (byte *p, Item_wr_ kt, int c)

add_item_to_block(p, kt_, c) adds item kt_ to the block at p.

void add_item (Item_wr_ kt, int j)

FlintTable::add_item(kt_, j) adds item kt_ to the block at cursor level C[j].

void delete_item (int j, bool repeatedly)

FlintTable::delete_item(j, repeatedly) is (almost) the converse of add_item.

int add_kt (bool found)

add_kt(found) adds the item (key-tag pair) at B->kt into the B-tree, using cursor C.

void read_root ()

void split_root (uint4 split_n)

Btree needs to gain a new level to insert more items: so split root block and construct a new one.

void form_key (const std::string &key) const

char other_base_letter () const

void lazy_alloc_deflate_zstream () const

Allocate the zstream for deflating, if not already allocated.

void lazy_alloc_inflate_zstream () const

Allocate the zstream for inflating, if not already allocated.

bool prev (Cursor_ *C_, int j) const

bool next (Cursor_ *C_, int j) const

bool prev_default (Cursor_ *C_, int j) const

bool next_default (Cursor_ *C_, int j) const

bool prev_for_sequential (Cursor_ *C_, int dummy) const

bool next_for_sequential (Cursor_ *C_, int dummy) const

XAPIAN_NORETURN (static void throw_database_closed())

Throw an exception indicating that the database is closed.

Static Protected Member Functions

static int find_in_block (const byte *p, Key_ key, bool leaf, int c)

find_in_block(p, key, leaf, c) searches for the key in the block at p.

static uint4 block_given_by (const byte *p, int c)

block_given_by(p, c) finds the item at block address p, directory offset c, and returns its tag value as an integer.

Protected Attributes

const char * tablename

The name of the table (used when writing changesets).

flint_revision_number_t revision_number

revision number of the opened B-tree.

uint4 item_count

keeps a count of the number of items in the B-tree.

unsigned int block_size

block size of the B tree in bytes

flint_revision_number_t latest_revision_number

Revision number of the other base, or zero if there is only one base file.

bool both_bases

set to true if baseA and baseB both exist as valid bases.

char base_letter

the value 'A' or 'B' of the current base

bool faked_root_block

true if the root block is faked (not written to disk).

bool sequential

true iff the data has been written in a single write in sequential order.

int handle

corresponding file handle

int level

number of levels, counting from 0

uint4 root

the root block of the B-tree

Item_wr_ kt

buffer of size block_size for making up key-tag items

byte * buffer

buffer of size block_size for reforming blocks

FlintTable_base base

For writing back as file baseA or baseB.

std::string name

The path name of the B tree.

int seq_count

count of the number of successive instances of purely sequential addition, starting at SEQ_START_POINT (neg) and going up to zero.

uint4 changed_n

the last block to be changed by an addition

int changed_c

directory offset corresponding to last block to be changed by an addition

size_t max_item_size

maximum size of an item (key-tag pair)

bool Btree_modified

Set to true the first time the B-tree is modified.

bool full_compaction

set to true when full compaction is to be achieved

bool writable

Set to true when the database is opened to write.

bool cursor_created_since_last_modification

Flag for tracking when cursors need to rebuild.

unsigned long cursor_version

Version count for tracking when cursors need to rebuild.

Cursor_ C [BTREE_CURSOR_LEVELS]

byte * split_p

Buffer used when splitting a block.

int compress_strategy

DONT_COMPRESS or Z_DEFAULT_STRATEGY, Z_FILTERED, Z_HUFFMAN_ONLY, Z_RLE.

z_stream * deflate_zstream

Zlib state object for deflating.

z_stream * inflate_zstream

Zlib state object for inflating.

bool lazy

If true, don't create the table until it's needed.

Private Member Functions

FlintTable (const FlintTable &)

Copying not allowed.

FlintTable & operator= (const FlintTable &)

Assignment not allowed.

bool really_empty () const

Return true if there are no entries in the table.

Friends

class FlintCursor

Detailed Description

Class managing a Btree table in a Flint database.

A table is a store holding a set of key/tag pairs.

A key is used to access a block of data in a flint table.

Keys are of limited length.

Keys may not be empty (each Btree has a special empty key for internal use).

A tag is a piece of data associated with a given key. The contents of the tag are opaque to the Btree.

Tags may be of arbitrary length (the Btree imposes a very large limit). Note though that they will be loaded into memory in their entirety, so should not be permitted to grow without bound in normal usage.

Tags which are null strings _are_ valid, and are different from a tag simply not being in the table.

Definition at line 263 of file flint_table.h.

Constructor & Destructor Documentation

FlintTable::FlintTable ( const FlintTable & ) [private]

Copying not allowed.

FlintTable::FlintTable	(	const char *	tablename_,
		const std::string &	path_,
		bool	readonly_,
		int	compress_strategy_ = `DONT_COMPRESS`,
		bool	lazy = `false`
	)

Create a new Btree object.

This does not create the table on disk - the create_and_open() method must be called to create the table on disk.

This also does not open the table - either the create_and_open() or open() methods must be called before use is made of the table.

Parameters:

	tablename_	The name of the table (used in changesets).
	path_	Path at which the table is stored.
	readonly_	whether to open the table for read only access.
	compress_strategy_	DONT_COMPRESS, Z_DEFAULT_STRATEGY, Z_FILTERED, Z_HUFFMAN_ONLY, or Z_RLE.
	lazy	If true, don't create the table until it's needed.

Definition at line 1539 of file flint_table.cc.

References LOGCALL_VOID.

FlintTable::~FlintTable ( )

Close the Btree.

Any outstanding changes (ie, changes made without commit() having subsequently been called) will be lost.

Definition at line 1728 of file flint_table.cc.

References close(), deflate_zstream, inflate_zstream, and LOGCALL_VOID.

Member Function Documentation

void FlintTable::add	(	const std::string &	key,
		std::string	tag,
		bool	already_compressed = `false`
	)

Add a key/tag pair to the table, replacing any existing pair with the same key.

If an error occurs during the operation, an exception will be thrown.

If key is empty, then the null item is replaced.

e.g. btree.add("TODAY", "Mon 9 Oct 2000");

Parameters:

	key	The key to store in the table.
	tag	The tag to store in the table.
	already_compressed	true if tag is already compressed, for example because it is being opaquely copied (default: false).

Definition at line 1008 of file flint_table.cc.

References add_kt(), Assert, block_size, Btree_modified, BYTE_PAIR_RANGE, C, C2, CompileTimeAssert, COMPRESS_MIN, compress_strategy, create_and_open(), cursor_created_since_last_modification, cursor_version, D2, deflate_zstream, delete_kt(), DONT_COMPRESS, find(), form_key(), full_compaction, handle, I2, item_count, K1, Item_base_< T >::key(), kt, lazy_alloc_deflate_zstream(), Key_::length(), LOGCALL_VOID, max_item_size, Cursor_::p, Item_wr_::set_component_of(), Item_wr_::set_components_of(), Item_wr_::set_tag(), TOTAL_FREE, and writable.

Referenced by FlintPostlistChunkWriter::flush(), FlintWritableDatabase::flush_postlist_changes(), FlintSynonymTable::merge_changes(), FlintSpellingTable::merge_changes(), FlintPostListTable::merge_changes(), FlintCompact::merge_docid_keyed(), FlintCompact::merge_postlists(), FlintCompact::merge_spellings(), FlintCompact::merge_synonyms(), FlintRecordTable::replace_record(), FlintValueTable::set_encoded_values(), FlintWritableDatabase::set_metadata(), FlintPositionListTable::set_positionlist(), and FlintTermListTable::set_termlist().

void FlintTable::add_item	(	Item_wr_	kt_,
		int	j
	)			`[protected]`

FlintTable::add_item(kt_, j) adds item kt_ to the block at cursor level C[j].

If there is not enough room the block splits and the item is then added to the appropriate half.

Definition at line 719 of file flint_table.cc.

References add_item_to_block(), Assert, base, block_size, Cursor_::c, C, changed_c, changed_n, compact(), D2, DIR_END, DIR_START, enter_key(), level, mid_point(), Cursor_::n, FlintTable_base::next_free_block(), Cursor_::p, seq_count, SET_DIR_END, Item_base_< T >::size(), split_p, split_root(), TOTAL_FREE, writable, and write_block().

Referenced by add_kt(), enter_key(), and split_root().

void FlintTable::add_item_to_block	(	byte *	p,
		Item_wr_	kt_,
		int	c
	)			`[protected]`

add_item_to_block(p, kt_, c) adds item kt_ to the block at p.

c is the offset in the directory that needs to be expanded to accommodate the new entry for the item. We know before this is called that there is enough room, so it's just a matter of byte shuffling.

Definition at line 682 of file flint_table.cc.

References Assert, compact(), D2, DIR_END, Item_base_< T >::get_address(), MAX_FREE, SET_DIR_END, SET_MAX_FREE, SET_TOTAL_FREE, setD, Item_base_< T >::size(), TOTAL_FREE, and writable.

Referenced by add_item().

int FlintTable::add_kt ( bool found ) [protected]

add_kt(found) adds the item (key-tag pair) at B->kt into the B-tree, using cursor C.

found == find() is handed over as a parameter from Btree::add. Btree::alter() prepares for the alteration to the B-tree. Then there are a number of cases to consider:

If an item with the same key is in the B-tree (found is true), the new kt replaces it.

If then kt is smaller, or the same size as, the item it replaces, kt is put in the same place as the item it replaces, and the TOTAL_FREE measure is reduced.

If kt is larger than the item it replaces it is put in the MAX_FREE space if there is room, and the directory entry and space counts are adjusted accordingly.

But if there is not room we do it the long way: the old item is deleted with delete_item and kt is added in with add_item.

If the key of kt is not in the B-tree (found is false), the new kt is added in with add_item.

Definition at line 881 of file flint_table.cc.

References add_item(), alter(), Assert, Cursor_::c, C, changed_c, changed_n, D2, delete_item(), DIR_END, Item_base_< T >::get_address(), kt, MAX_FREE, Cursor_::p, seq_count, SEQ_START_POINT, sequential, SET_MAX_FREE, SET_TOTAL_FREE, setD, Item_base_< T >::size(), TOTAL_FREE, and writable.

Referenced by add().

void FlintTable::alter ( ) [protected]

Btree::alter(); is called when the B-tree is to be altered.

It causes new blocks to be forced for the current set of blocks in the cursor.

The point is that if a block at level 0 is to be altered it may get a new number. Then the pointer to this block from level 1 will need changing. So the block at level 1 needs altering and may get a new block number. Then the pointer to this block from level 2 will need changing ... and so on back to the root.

The clever bit here is spotting the cases when we can make an early exit from this process. If C[j].rewrite is true, C[j+k].rewrite will be true for k = 1,2 ... We have been through all this before, and there is no need to do it again. If C[j].n was free at the start of the transaction, we can copy it back to the same place without violating the integrity of the B-tree. We don't then need a new n and can return. The corresponding C[j].rewrite may be true or false in that case.

Definition at line 417 of file flint_table.cc.

References Assert, base, FlintTable_base::block_free_at_start(), C, FlintTable_base::free_block(), latest_revision_number, level, LOGCALL_VOID, Cursor_::n, FlintTable_base::next_free_block(), Cursor_::p, REVISION, Cursor_::rewrite, SET_REVISION, and writable.

Referenced by add_kt(), and delete_kt().

bool FlintTable::basic_open	(	bool	revision_supplied,
		flint_revision_number_t	revision
	)			`[protected]`

static uint4 FlintTable::block_given_by	(	const byte *	p,
		int	c
	)			`[static, protected]`

block_given_by(p, c) finds the item at block address p, directory offset c, and returns its tag value as an integer.

Referenced by BtreeCheck::block_check(), find(), next_default(), and prev_default().

void FlintTable::block_to_cursor	(	Cursor_ *	C_,
		int	j,
		uint4	n
	)			const `[protected]`

Definition at line 361 of file flint_table.cc.

References Assert, AssertEq, block_size, C, GET_LEVEL, level, LOGCALL_VOID, Cursor_::n, Cursor_::p, read_block(), REVISION, Cursor_::rewrite, writable, and write_block().

Referenced by BtreeCheck::block_check(), delete_item(), find(), next_default(), prev_default(), and read_root().

void FlintTable::cancel ( )

Cancel any outstanding changes.

This will discard any modifications which haven't been committed by calling commit().

Reimplemented in FlintSpellingTable, and FlintSynonymTable.

Definition at line 1937 of file flint_table.cc.

References Assert, base, base_letter, BLK_UNUSED, block_size, Btree_modified, C, changed_c, changed_n, DIR_START, faked_root_block, FlintTable_base::get_block_size(), FlintTable_base::get_have_fakeroot(), FlintTable_base::get_item_count(), FlintTable_base::get_level(), FlintTable_base::get_revision(), FlintTable_base::get_root(), FlintTable_base::get_sequential(), handle, item_count, latest_revision_number, level, LOGCALL_VOID, Cursor_::n, FlintTable_base::read(), read_root(), revision_number, Cursor_::rewrite, root, seq_count, SEQ_START_POINT, sequential, and writable.

Referenced by FlintDatabase::cancel().

void FlintTable::close ( bool permanent = false )

Close the Btree.

This closes and frees any of the btree structures which have been created and opened.

Parameters:

permanent

If true, the Btree will not reopen on demand.

Definition at line 1747 of file flint_table.cc.

References buffer, C, Item_base_< T >::get_address(), handle, kt, level, LOGCALL_VOID, Cursor_::p, and split_p.

Referenced by basic_open(), FlintDatabase::close(), commit(), create_and_open(), do_open_to_read(), do_open_to_write(), erase(), open(), and ~FlintTable().

void FlintTable::commit	(	flint_revision_number_t	revision,
		int	changes_fd = `-1`,
		const std::string *	changes_tail = `NULL`
	)

Commit any outstanding changes to the table.

Commit changes made by calling add() and del() to the Btree.

If an error occurs during the operation, this will be signalled by an exception. In case of error, changes made will not be committed to the Btree - they will be discarded.

Parameters:

	new_revision	The new revision number to store. This must be greater than the latest revision number (see get_latest_revision_number()), or an exception will be thrown.
	changes_fd	The file descriptor to write changes to. Defaults to -1, meaning no changes will be written.

Definition at line 1801 of file flint_table.cc.

References Assert, base, base_letter, BLK_UNUSED, both_bases, BTREE_CURSOR_LEVELS, Btree_modified, Cursor_::c, C, changed_c, changed_n, FlintTable_base::clear_bit_map(), close(), FlintTable_base::commit(), DIR_START, faked_root_block, handle, io_sync(), item_count, latest_revision_number, level, LOGCALL_VOID, msvc_posix_rename(), Cursor_::n, other_base_letter(), read_root(), revision_number, Cursor_::rewrite, root, seq_count, SEQ_START_POINT, sequential, FlintTable_base::set_have_fakeroot(), FlintTable_base::set_item_count(), FlintTable_base::set_level(), FlintTable_base::set_revision(), FlintTable_base::set_root(), FlintTable_base::set_sequential(), tablename, unlink(), writable, and FlintTable_base::write_to_file().

Referenced by compact_flint(), FlintCompact::multimerge_postlists(), and FlintDatabase::set_revision_number().

void FlintTable::compact ( byte * p ) [protected]

compact(p) compact the block at p by shuffling all the items up to the end.

MAX_FREE(p) is then maximized, and is equal to TOTAL_FREE(p).

Definition at line 525 of file flint_table.cc.

References Assert, block_size, buffer, D2, DIR_END, DIR_START, Item_base_< T >::get_address(), LOGCALL_VOID, SET_MAX_FREE, SET_TOTAL_FREE, setD, Item_base_< T >::size(), and writable.

Referenced by add_item(), add_item_to_block(), and split_root().

void FlintTable::create_and_open ( unsigned int blocksize )

Create a new empty btree structure on disk and open it at the initial revision.

The table must be writable - it doesn't make sense to create a table that is read-only!

The block size must be less than 64K, where K = 1024. It is unwise to use a small block size (less than 1024 perhaps), so we enforce a minimum block size of 2K.

Example:

Btree btree("X-"); btree.create_and_open(8192); // Files will be X-DB, X-baseA (and X-baseB).

Parameters:

blocksize

- Size of blocks to use.

Exceptions:

	Xapian::DatabaseCreateError	if the table can't be created.
	Xapian::InvalidArgumentError	if the requested blocksize is unsuitable.

Reimplemented in FlintSpellingTable, and FlintSynonymTable.

Definition at line 1695 of file flint_table.cc.

References Assert, close(), do_open_to_write(), handle, io_unlink(), LOGCALL_VOID, revision_number, FlintTable_base::set_block_size(), set_block_size(), FlintTable_base::set_have_fakeroot(), FlintTable_base::set_revision(), FlintTable_base::set_sequential(), writable, and FlintTable_base::write_to_file().

Referenced by add(), compact_flint(), FlintDatabase::create_and_open_tables(), and FlintCompact::multimerge_postlists().

FlintCursor * FlintTable::cursor_get ( ) const

Get a cursor for reading from the table.

The cursor is owned by the caller - it is the caller's responsibility to ensure that it is deleted.

Definition at line 1298 of file flint_table.cc.

References FlintCursor, and handle.

Referenced by check_flint_table(), FlintPostlistChunkWriter::flush(), FlintPostListTable::get_chunk(), FlintPostListTable::merge_changes(), FlintDatabase::open_metadata_keylist(), FlintDatabase::open_spelling_wordlist(), and FlintDatabase::open_synonym_keylist().

bool FlintTable::del ( const std::string & key )

Delete an entry from the table.

The entry will be removed from the table, if it exists. If it does not exist, no action will be taken. The item with an empty key can't be removed, and false is returned.

If an error occurs during the operation, this will be signalled by an exception.

e.g. bool deleted = btree.del("TODAY")

Parameters:

key

The key to remove from the table.

Returns:: true if an entry was removed; false if it did not exist.

Definition at line 1132 of file flint_table.cc.

References Assert, Btree_modified, cursor_created_since_last_modification, cursor_version, delete_kt(), FLINT_BTREE_MAX_KEY_LEN, form_key(), handle, item_count, kt, LOGCALL, RETURN, Item_wr_::set_component_of(), and writable.

Referenced by FlintCursor::del(), FlintValueTable::delete_all_values(), FlintPositionListTable::delete_positionlist(), FlintRecordTable::delete_record(), FlintTermListTable::delete_termlist(), FlintPostlistChunkWriter::flush(), FlintSynonymTable::merge_changes(), FlintSpellingTable::merge_changes(), FlintPostListTable::merge_changes(), and FlintWritableDatabase::set_metadata().

void FlintTable::delete_item	(	int	j,
		bool	repeatedly
	)			`[protected]`

FlintTable::delete_item(j, repeatedly) is (almost) the converse of add_item.

If repeatedly is true, the process repeats at the next level when a block has been completely emptied, freeing the block and taking out the pointer to it. Emptied root blocks are also removed, which reduces the number of levels in the B-tree.

Definition at line 809 of file flint_table.cc.

References Assert, base, BLK_UNUSED, block_to_cursor(), Cursor_::c, C, D2, DIR_END, DIR_START, FlintTable_base::free_block(), level, MAX_FREE, Cursor_::n, Cursor_::p, Cursor_::rewrite, SET_DIR_END, SET_MAX_FREE, SET_TOTAL_FREE, TOTAL_FREE, and writable.

Referenced by add_kt(), and delete_kt().

int FlintTable::delete_kt ( ) [protected]

Definition at line 946 of file flint_table.cc.

References alter(), Assert, C, delete_item(), find(), seq_count, SEQ_START_POINT, sequential, and writable.

Referenced by add(), and del().

bool FlintTable::do_open_to_read	(	bool	revision_supplied,
		flint_revision_number_t	revision_
	)			`[protected]`

Perform the opening operation to read.

Return true iff the open succeeded.

Definition at line 1984 of file flint_table.cc.

References basic_open(), BLK_UNUSED, block_size, C, close(), handle, lazy, level, Cursor_::n, O_BINARY, open(), Cursor_::p, read_root(), and revision_number.

Referenced by open().

bool FlintTable::do_open_to_write	(	bool	revision_supplied,
		flint_revision_number_t	revision_,
		bool	create_db = `false`
	)			`[protected]`

Perform the opening operation to write.

Return true iff the open succeeded.

Definition at line 1479 of file flint_table.cc.

References basic_open(), BLK_UNUSED, block_size, buffer, C, changed_c, changed_n, close(), DIR_START, handle, lazy, level, Cursor_::n, O_BINARY, open(), Cursor_::p, read_root(), revision_number, seq_count, SEQ_START_POINT, split_p, writable, and zeroed_new().

Referenced by create_and_open(), and open().

bool FlintTable::empty ( ) const [inline]

Return true if there are no entries in the table.

Definition at line 536 of file flint_table.h.

References FlintCursor::level.

Referenced by copy_docid_keyed(), copy_position(), copy_postlist(), copy_termlist(), copy_unchanged(), FlintDatabase::has_positions(), main(), FlintCompact::merge_docid_keyed(), FlintCompact::merge_postlists(), FlintCompact::merge_spellings(), and FlintCompact::merge_synonyms().

void FlintTable::enter_key	(	int	j,
		Key_	prevkey,
		Key_	newkey
	)			`[protected]`

enter_key(j, prevkey, newkey) is called after a block split.

It enters in the block at level C[j] a separating key for the block at level C[j - 1]. The key itself is newkey. prevkey is the preceding key, and at level 1 newkey can be trimmed down to the first point of difference to prevkey for entry in C[j].

This code looks longer than it really is. If j exceeds the number of B-tree levels the root block has split and we have to construct a new one, but this is a rare event.

The key is constructed in b, with block number C[j - 1].n as tag, and this is added in with add_item. add_item may itself cause a block split, with a further call to enter_key. Hence the recursion.

Definition at line 594 of file flint_table.cc.

References add_item(), Assert, Cursor_::c, C, C2, D2, find_in_block(), Key_::get_address(), getint4(), I2, K1, Item_base_< T >::key(), Key_::length(), Cursor_::n, Cursor_::p, Cursor_::rewrite, Item_wr_::set_key_and_block(), SET_TOTAL_FREE, TOTAL_FREE, and writable.

Referenced by add_item().

void FlintTable::erase ( )

Erase this table from disk.

Definition at line 1672 of file flint_table.cc.

References close(), io_unlink(), and LOGCALL_VOID.

Referenced by compact_flint(), FlintSynonymTable::create_and_open(), FlintSpellingTable::create_and_open(), and FlintDatabase::create_and_open_tables().

bool FlintTable::exists ( ) const

Determine whether the btree exists on disk.

Definition at line 1665 of file flint_table.cc.

References file_exists(), and LOGCALL.

Referenced by FlintDatabase::database_exists().

bool FlintTable::find ( Cursor_ * C_ ) const [protected]

find(C_) searches for the key of B->kt in the B-tree.

Result is true if found, false otherwise. When false, the B_tree cursor is positioned at the last key in the B-tree <= the search key. Goes to first (null) item in B-tree when key length == 0.

Definition at line 491 of file flint_table.cc.

References block_given_by(), block_to_cursor(), DIR_START, find_in_block(), Item_base_< T >::key(), kt, level, LOGCALL, Key_::p, and RETURN.

Referenced by add(), delete_kt(), FlintCursor::find_entry(), FlintCursor::find_entry_ge(), get_exact_entry(), and key_exists().

int FlintTable::find_in_block	(	const byte *	p,
		Key_	key,
		bool	leaf,
		int	c
	)			`[static, protected]`

find_in_block(p, key, leaf, c) searches for the key in the block at p.

leaf is true for a data block, and false for an index block (when the first key is dummy and never needs to be tested). What we get is the directory entry to the last key <= the key being searched for.

The lookup is by binary chop, with i and j set to the left and right ends of the search area. In sequential addition, c will often be the answer, so we test the keys round c and move i and j towards c if possible.

Definition at line 461 of file flint_table.cc.

References D2, DIR_END, DIR_START, Key_::get_address(), LOGCALL_STATIC, and RETURN.

Referenced by enter_key(), and find().

void FlintTable::flush_db ( )

Flush any outstanding changes to the DB file of the table.

This must be called before commit, to ensure that the DB file is ready to be switched to a new version by the commit.

Reimplemented in FlintSpellingTable, and FlintSynonymTable.

Definition at line 1778 of file flint_table.cc.

References Assert, Btree_modified, C, faked_root_block, handle, level, LOGCALL_VOID, writable, and write_block().

Referenced by compact_flint(), FlintCompact::multimerge_postlists(), and FlintDatabase::set_revision_number().

void FlintTable::form_key ( const std::string & key ) const [protected]

Definition at line 979 of file flint_table.cc.

References Item_wr_::form_key(), and kt.

Referenced by add(), del(), FlintCursor::find_entry(), FlintCursor::find_entry_ge(), get_exact_entry(), and key_exists().

unsigned int FlintTable::get_block_size ( ) const [inline]

Get the block size.

Definition at line 467 of file flint_table.h.

Referenced by FlintDatabase::open_tables(), and FlintDatabase::open_tables_consistent().

flint_tablesize_t FlintTable::get_entry_count ( ) const [inline]

Return a count of the number of entries in the table.

The count does not include the ever-present item with null key.

Use empty() if you only want to know if the table is empty or not.

Returns:: The number of entries in the table.

Definition at line 531 of file flint_table.h.

Referenced by FlintRecordTable::get_doccount().

bool FlintTable::get_exact_entry	(	const std::string &	key,
		std::string &	tag
	)			const

Read an entry from the table, if and only if it is exactly that being asked for.

If the key is found in the table, then the tag is copied to tag. If the key is not found tag is left unchanged.

The result is true iff the specified key is found in the Btree.

Parameters:

	key	The key to look for in the table.
	tag	A tag object to fill with the value if found.

Returns:: true if key is found in table, false if key is not found in table.

Definition at line 1168 of file flint_table.cc.

References Assert, C, find(), FLINT_BTREE_MAX_KEY_LEN, form_key(), handle, LOGCALL, read_tag(), and RETURN.

Referenced by FlintSynonymTable::add_synonym(), FlintSpellingTable::add_word(), FlintPostlistChunkWriter::flush(), FlintValueTable::get_all_values(), FlintPostListTable::get_collection_freq(), FlintTermListTable::get_doclength(), FlintDatabase::get_metadata(), FlintRecordTable::get_record(), FlintPostListTable::get_termfreq(), FlintValueTable::get_value(), FlintSpellingTable::get_word_frequency(), FlintSpellingTable::merge_changes(), FlintPostListTable::merge_changes(), FlintSynonymTable::open_termlist(), FlintSpellingTable::open_termlist(), FlintPositionListTable::positionlist_count(), FlintPositionList::read_data(), FlintDatabase::read_metainfo(), FlintSynonymTable::remove_synonym(), FlintSpellingTable::remove_word(), and FlintPositionListTable::set_positionlist().

flint_revision_number_t FlintTable::get_latest_revision_number ( ) const [inline]

Get the latest revision number stored in this table.

This gives the higher of the revision numbers held in the base files of the B-tree, or just the revision number if there's only one base file.

It is possible that there are other, older, revisions of this table available, and indeed that the revision currently open is one of these older revisions.

Definition at line 506 of file flint_table.h.

Referenced by FlintDatabase::FlintDatabase(), and FlintDatabase::get_next_revision_number().

flint_revision_number_t FlintTable::get_open_revision_number ( ) const [inline]

Get the revision number at which this table is currently open.

It is possible that there are other, more recent or older revisions available.

Returns:: the current revision number.

Definition at line 518 of file flint_table.h.

Referenced by FlintDatabaseReplicator::apply_changeset_from_conn(), FlintDatabase::create_and_open_tables(), FlintDatabase::FlintDatabase(), FlintDatabase::get_revision_number(), and FlintDatabase::open_tables_consistent().

bool FlintTable::is_modified ( ) const [inline]

Determine whether the object contains uncommitted modifications.

Returns:: true if there have been modifications since the last the last call to commit().

Reimplemented in FlintSpellingTable, and FlintSynonymTable.

Definition at line 561 of file flint_table.h.

Referenced by FlintDatabase::apply().

bool FlintTable::key_exists ( const std::string & key ) const

Check if a key exists in the Btree.

This is just like get_exact_entry() except it doesn't read the tag value so is more efficient if you only want to check that the key exists.

Parameters:

key

The key to look for in the table.

Returns:: true if key is found in table, false if key is not found in table.

Definition at line 1191 of file flint_table.cc.

References Assert, C, find(), FLINT_BTREE_MAX_KEY_LEN, form_key(), LOGCALL, and RETURN.

Referenced by FlintPostListTable::term_exists().

void FlintTable::lazy_alloc_deflate_zstream ( ) const [protected]

Allocate the zstream for deflating, if not already allocated.

Definition at line 1590 of file flint_table.cc.

References compress_strategy, deflate_zstream, rare, Xapian::Internal::str(), and usual.

Referenced by add().

void FlintTable::lazy_alloc_inflate_zstream ( ) const [protected]

Allocate the zstream for inflating, if not already allocated.

Definition at line 1628 of file flint_table.cc.

References inflate_zstream, rare, Xapian::Internal::str(), and usual.

Referenced by read_tag().

int FlintTable::mid_point ( byte * p ) [protected]

mid_point(p) finds the directory entry in c that determines the approximate mid point of the data in the block at p.

Definition at line 654 of file flint_table.cc.

References Assert, block_size, D2, DIR_END, DIR_START, and TOTAL_FREE.

Referenced by add_item().

bool FlintTable::next	(	Cursor_ *	C_,
		int	j
	)			const `[inline, protected]`

Definition at line 713 of file flint_table.h.

Referenced by FlintCursor::find_entry_ge(), FlintCursor::next(), read_tag(), and FlintCursor::read_tag().

bool FlintTable::next_default	(	Cursor_ *	C_,
		int	j
	)			const `[protected]`

Definition at line 2198 of file flint_table.cc.

References Assert, block_given_by(), block_size, block_to_cursor(), Cursor_::c, D2, DIR_END, DIR_START, level, and Cursor_::p.

bool FlintTable::next_for_sequential	(	Cursor_ *	C_,
		int	dummy
	)			const `[protected]`

Definition at line 2125 of file flint_table.cc.

References Assert, AssertEq, base, block_size, C, Cursor_::c, D2, DIR_END, DIR_START, FlintTable_base::get_last_block(), GET_LEVEL, latest_revision_number, level, Cursor_::n, Cursor_::p, read_block(), REVISION, revision_number, and writable.

bool FlintTable::open ( flint_revision_number_t revision_ )

Open the btree at a given revision.

Like Btree::open, but try to open at the given revision number and fail if that isn't possible.

Parameters:

revision_

- revision number to open.

Returns:: true if table is successfully opened at desired revision; false if table cannot be opened at desired revision (but table is otherwise consistent).

Exceptions:

	Xapian::DatabaseCorruptError	will be thrown if the table is in a corrupt state.
	Xapian::DatabaseOpeningError	will be thrown if the table cannot be opened (but is not corrupt - eg, permission problems, not present, etc).

Definition at line 2046 of file flint_table.cc.

References AssertEq, close(), do_open_to_read(), do_open_to_write(), LOGCALL, LOGLINE, RETURN, revision_number, and writable.

void FlintTable::open ( )

Open the btree at the latest revision.

Exceptions:

	Xapian::DatabaseCorruptError	will be thrown if the table is in a corrupt state.
	Xapian::DatabaseOpeningError	will be thrown if the table cannot be opened (but is not corrupt - eg, permission problems, not present, etc).

Definition at line 2029 of file flint_table.cc.

References close(), do_open_to_read(), do_open_to_write(), LOGCALL_VOID, LOGLINE, and writable.

Referenced by FlintDatabaseReplicator::apply_changeset_from_conn(), BtreeCheck::check(), check_flint_table(), copy_docid_keyed(), copy_position(), copy_postlist(), copy_termlist(), copy_unchanged(), do_open_to_read(), do_open_to_write(), main(), FlintCompact::merge_docid_keyed(), FlintCompact::merge_postlists(), FlintCompact::merge_spellings(), FlintCompact::merge_synonyms(), FlintDatabase::open_tables(), and FlintDatabase::open_tables_consistent().

FlintTable& FlintTable::operator= ( const FlintTable & ) [private]

Assignment not allowed.

char FlintTable::other_base_letter ( ) const [inline, protected]

Definition at line 612 of file flint_table.h.

Referenced by commit(), and write_block().

bool FlintTable::prev	(	Cursor_ *	C_,
		int	j
	)			const `[inline, protected]`

Definition at line 708 of file flint_table.h.

Referenced by FlintCursor::find_entry(), and FlintCursor::prev().

bool FlintTable::prev_default	(	Cursor_ *	C_,
		int	j
	)			const `[protected]`

Definition at line 2177 of file flint_table.cc.

References Assert, block_given_by(), block_size, block_to_cursor(), Cursor_::c, D2, DIR_END, DIR_START, level, and Cursor_::p.

bool FlintTable::prev_for_sequential	(	Cursor_ *	C_,
		int	dummy
	)			const `[protected]`

Definition at line 2073 of file flint_table.cc.

References Assert, AssertEq, block_size, C, Cursor_::c, D2, DIR_END, DIR_START, GET_LEVEL, latest_revision_number, level, Cursor_::n, Cursor_::p, read_block(), REVISION, revision_number, and writable.

void FlintTable::read_block	(	uint4	n,
		byte *	p
	)			const `[protected]`

read_block(n, p) reads block n of the DB file to address p.

Definition at line 203 of file flint_table.cc.

References Assert, base, block_size, FlintTable_base::get_bit_map_size(), handle, io_read(), LOGCALL_VOID, and Xapian::Internal::str().

Referenced by block_to_cursor(), next_for_sequential(), prev_for_sequential(), and write_changed_blocks().

void FlintTable::read_root ( ) [protected]

Definition at line 1436 of file flint_table.cc.

References Assert, base, block_size, block_to_cursor(), C, C2, D2, DIR_START, faked_root_block, I2, K1, latest_revision_number, level, Cursor_::n, FlintTable_base::next_free_block(), Cursor_::p, REVISION, revision_number, root, SET_DIR_END, SET_LEVEL, SET_MAX_FREE, SET_REVISION, SET_TOTAL_FREE, setD, and writable.

Referenced by cancel(), commit(), do_open_to_read(), and do_open_to_write().

bool FlintTable::read_tag	(	Cursor_ *	C_,
		std::string *	tag,
		bool	keep_compressed
	)			const

Read the tag value for the key pointed to by cursor C_.

Parameters:

keep_compressed

Don't uncompress the tag - e.g. useful if it's just being opaquely copied.

Returns:: true if current_tag holds compressed data (always false if keep_compressed was false).

Definition at line 1204 of file flint_table.cc.

References Item_base_< T >::append_chunk(), C2, Item_base_< T >::components_of(), Item_base_< T >::get_compressed(), I2, inflate_zstream, K1, lazy_alloc_inflate_zstream(), LOGLINE, max_item_size, next(), setint4(), and Xapian::Internal::str().

Referenced by get_exact_entry(), and FlintCursor::read_tag().

bool FlintTable::really_empty ( ) const [private]

Return true if there are no entries in the table.

Definition at line 1576 of file flint_table.cc.

References FlintCursor::find_entry(), handle, and FlintCursor::next().

void FlintTable::set_block_size ( unsigned int block_size_ )

Set the block size.

It's only safe to do this before the table is created.

Definition at line 1683 of file flint_table.cc.

References block_size, BYTE_PAIR_RANGE, FLINT_DEFAULT_BLOCK_SIZE, and LOGCALL_VOID.

Referenced by compact_flint(), create_and_open(), FlintSynonymTable::create_and_open(), FlintSpellingTable::create_and_open(), FlintDatabase::create_and_open_tables(), FlintDatabase::open_tables(), and FlintDatabase::open_tables_consistent().

void FlintTable::set_full_compaction ( bool parity )

Definition at line 1290 of file flint_table.cc.

References Assert, full_compaction, seq_count, and writable.

Referenced by compact_flint().

void FlintTable::set_max_item_size ( size_t block_capacity ) [inline]

Set the maximum item size given the block capacity.

At least this many items of maximum size must fit into a block. The default is BLOCK_CAPACITY (which is currently 4).

Definition at line 568 of file flint_table.h.

References BLOCK_CAPACITY, and D2.

Referenced by basic_open(), and compact_flint().

void FlintTable::split_root ( uint4 split_n ) [protected]

Btree needs to gain a new level to insert more items: so split root block and construct a new one.

Definition at line 549 of file flint_table.cc.

References add_item(), base, block_size, BTREE_CURSOR_LEVELS, Cursor_::c, C, compact(), DIR_START, Item_wr_::form_null_key(), latest_revision_number, level, LOGCALL_VOID, Cursor_::n, FlintTable_base::next_free_block(), Cursor_::p, Cursor_::rewrite, SET_DIR_END, SET_LEVEL, SET_REVISION, STRINGIZE, and zeroed_new().

Referenced by add_item().

void FlintTable::write_block	(	uint4	n,
		const byte *	p
	)			const `[protected]`

write_block(n, p) writes block n in the DB file from address p.

When writing we check to see if the DB file has already been modified. If not (so this is the first write) the old base is deleted. This prevents the possibility of it being opened subsequently as an invalid base.

Definition at line 255 of file flint_table.cc.

References Assert, AssertEqParanoid, AssertParanoid, base, FlintTable_base::block_free_at_start(), block_size, both_bases, FlintTable_base::get_bit_map_size(), handle, io_unlink(), io_write(), latest_revision_number, LOGCALL_VOID, other_base_letter(), REVISION, revision_number, and writable.

Referenced by add_item(), block_to_cursor(), and flush_db().

void FlintTable::write_changed_blocks ( int changes_fd )

Append the list of blocks changed to a changeset file.

Parameters:

changes_fd

The file descriptor to write changes to.

Definition at line 1896 of file flint_table.cc.

References Assert, base, block_size, FlintTable_base::calculate_last_block(), F_pack_uint(), faked_root_block, FlintTable_base::find_changed_block(), handle, io_write(), read_block(), and tablename.

Referenced by FlintDatabase::set_revision_number().

FlintTable::XAPIAN_NORETURN ( static void throw_database_closed() ) [protected]

Throw an exception indicating that the database is closed.

FlintTable::XAPIAN_NORETURN ( void set_overwritten() const ) [protected]

Friends And Related Function Documentation

friend class FlintCursor [friend]

Definition at line 264 of file flint_table.h.

Referenced by cursor_get().

Member Data Documentation

FlintTable_base FlintTable::base [protected]

For writing back as file baseA or baseB.

Definition at line 672 of file flint_table.h.

Referenced by add_item(), alter(), basic_open(), BtreeCheck::block_check(), cancel(), BtreeCheck::check(), commit(), delete_item(), next_for_sequential(), read_block(), read_root(), split_root(), write_block(), and write_changed_blocks().

char FlintTable::base_letter [protected]

the value 'A' or 'B' of the current base

Definition at line 643 of file flint_table.h.

Referenced by basic_open(), cancel(), BtreeCheck::check(), and commit().

unsigned int FlintTable::block_size [protected]

block size of the B tree in bytes

Definition at line 629 of file flint_table.h.

Referenced by add(), add_item(), basic_open(), BtreeCheck::block_check(), block_to_cursor(), BtreeCheck::block_usage(), cancel(), BtreeCheck::check(), compact(), do_open_to_read(), do_open_to_write(), FlintCursor::FlintCursor(), mid_point(), next_default(), next_for_sequential(), prev_default(), prev_for_sequential(), read_block(), read_root(), FlintCursor::rebuild(), set_block_size(), split_root(), write_block(), and write_changed_blocks().

bool FlintTable::both_bases [mutable, protected]

set to true if baseA and baseB both exist as valid bases.

The unused base is deleted as soon as a write to the Btree takes place.

Definition at line 640 of file flint_table.h.

Referenced by basic_open(), commit(), and write_block().

bool FlintTable::Btree_modified [mutable, protected]

Set to true the first time the B-tree is modified.

Definition at line 693 of file flint_table.h.

Referenced by add(), cancel(), commit(), del(), and flush_db().

byte* FlintTable::buffer [protected]

buffer of size block_size for reforming blocks

Definition at line 669 of file flint_table.h.

Referenced by close(), compact(), and do_open_to_write().

Cursor_ FlintTable::C[BTREE_CURSOR_LEVELS] [mutable, protected]

Definition at line 733 of file flint_table.h.

Referenced by add(), add_item(), add_kt(), alter(), block_to_cursor(), cancel(), BtreeCheck::check(), close(), commit(), delete_item(), delete_kt(), do_open_to_read(), do_open_to_write(), enter_key(), FlintCursor::FlintCursor(), flush_db(), get_exact_entry(), key_exists(), next_for_sequential(), prev_for_sequential(), read_root(), FlintCursor::rebuild(), and split_root().

int FlintTable::changed_c [protected]

directory offset corresponding to last block to be changed by an addition

Definition at line 687 of file flint_table.h.

Referenced by add_item(), add_kt(), cancel(), commit(), and do_open_to_write().

uint4 FlintTable::changed_n [protected]

the last block to be changed by an addition

Definition at line 683 of file flint_table.h.

Referenced by add_item(), add_kt(), cancel(), commit(), and do_open_to_write().

int FlintTable::compress_strategy [protected]

DONT_COMPRESS or Z_DEFAULT_STRATEGY, Z_FILTERED, Z_HUFFMAN_ONLY, Z_RLE.

Definition at line 744 of file flint_table.h.

Referenced by add(), and lazy_alloc_deflate_zstream().

bool FlintTable::cursor_created_since_last_modification [mutable, protected]

Flag for tracking when cursors need to rebuild.

Definition at line 702 of file flint_table.h.

Referenced by add(), del(), and FlintCursor::FlintCursor().

unsigned long FlintTable::cursor_version [protected]

Version count for tracking when cursors need to rebuild.

Definition at line 705 of file flint_table.h.

Referenced by add(), del(), FlintCursor::find_entry(), FlintCursor::find_entry_ge(), FlintCursor::next(), FlintCursor::prev(), and FlintCursor::rebuild().

z_stream* FlintTable::deflate_zstream [mutable, protected]

Zlib state object for deflating.

Definition at line 747 of file flint_table.h.

Referenced by add(), lazy_alloc_deflate_zstream(), and ~FlintTable().

bool FlintTable::faked_root_block [protected]

true if the root block is faked (not written to disk).

false otherwise. This is true when the btree hasn't been modified yet.

Definition at line 649 of file flint_table.h.

Referenced by basic_open(), cancel(), BtreeCheck::check(), commit(), flush_db(), read_root(), and write_changed_blocks().

bool FlintTable::full_compaction [protected]

set to true when full compaction is to be achieved

Definition at line 696 of file flint_table.h.

Referenced by add(), and set_full_compaction().

int FlintTable::handle [protected]

corresponding file handle

Definition at line 657 of file flint_table.h.

Referenced by add(), basic_open(), cancel(), close(), commit(), create_and_open(), cursor_get(), del(), do_open_to_read(), do_open_to_write(), flush_db(), get_exact_entry(), read_block(), really_empty(), write_block(), and write_changed_blocks().

z_stream* FlintTable::inflate_zstream [mutable, protected]

Zlib state object for inflating.

Definition at line 750 of file flint_table.h.

Referenced by lazy_alloc_inflate_zstream(), read_tag(), and ~FlintTable().

uint4 FlintTable::item_count [protected]

keeps a count of the number of items in the B-tree.

Definition at line 626 of file flint_table.h.

Referenced by add(), basic_open(), cancel(), BtreeCheck::check(), commit(), and del().

Item_wr_ FlintTable::kt [mutable, protected]

buffer of size block_size for making up key-tag items

Definition at line 666 of file flint_table.h.

Referenced by add(), add_kt(), basic_open(), close(), del(), find(), and form_key().

flint_revision_number_t FlintTable::latest_revision_number [mutable, protected]

Revision number of the other base, or zero if there is only one base file.

Definition at line 634 of file flint_table.h.

Referenced by alter(), basic_open(), cancel(), commit(), next_for_sequential(), prev_for_sequential(), read_root(), split_root(), and write_block().

bool FlintTable::lazy [protected]

If true, don't create the table until it's needed.

Definition at line 753 of file flint_table.h.

Referenced by compact_flint(), do_open_to_read(), and do_open_to_write().

int FlintTable::level [protected]

number of levels, counting from 0

Definition at line 660 of file flint_table.h.

Referenced by add_item(), alter(), basic_open(), BtreeCheck::block_check(), block_to_cursor(), cancel(), BtreeCheck::check(), close(), commit(), delete_item(), do_open_to_read(), do_open_to_write(), find(), flush_db(), FlintCursor::get_key(), next_default(), next_for_sequential(), prev_default(), prev_for_sequential(), read_root(), FlintCursor::read_tag(), FlintCursor::rebuild(), BtreeCheck::report_cursor(), and split_root().

size_t FlintTable::max_item_size [protected]

maximum size of an item (key-tag pair)

Definition at line 690 of file flint_table.h.

Referenced by add(), and read_tag().

std::string FlintTable::name [protected]

The path name of the B tree.

Definition at line 675 of file flint_table.h.

flint_revision_number_t FlintTable::revision_number [protected]

revision number of the opened B-tree.

Definition at line 623 of file flint_table.h.

Referenced by basic_open(), cancel(), BtreeCheck::check(), commit(), create_and_open(), do_open_to_read(), do_open_to_write(), next_for_sequential(), open(), prev_for_sequential(), read_root(), and write_block().

uint4 FlintTable::root [protected]

the root block of the B-tree

Definition at line 663 of file flint_table.h.

Referenced by basic_open(), cancel(), commit(), and read_root().

int FlintTable::seq_count [protected]

count of the number of successive instances of purely sequential addition, starting at SEQ_START_POINT (neg) and going up to zero.

Definition at line 680 of file flint_table.h.

Referenced by add_item(), add_kt(), cancel(), commit(), delete_kt(), do_open_to_write(), and set_full_compaction().

bool FlintTable::sequential [protected]

true iff the data has been written in a single write in sequential order.

Definition at line 654 of file flint_table.h.

Referenced by add_kt(), basic_open(), cancel(), commit(), and delete_kt().

byte* FlintTable::split_p [protected]

Buffer used when splitting a block.

This buffer holds the split off part of the block. It's only used when updating (in FlintTable::add_item().

Definition at line 740 of file flint_table.h.

Referenced by add_item(), close(), and do_open_to_write().

const char* FlintTable::tablename [protected]

The name of the table (used when writing changesets).

Definition at line 610 of file flint_table.h.

Referenced by commit(), and write_changed_blocks().

bool FlintTable::writable [protected]

Set to true when the database is opened to write.

Definition at line 699 of file flint_table.h.

Referenced by add(), add_item(), add_item_to_block(), add_kt(), alter(), basic_open(), block_to_cursor(), cancel(), commit(), compact(), create_and_open(), del(), delete_item(), delete_kt(), do_open_to_write(), enter_key(), flush_db(), next_for_sequential(), open(), prev_for_sequential(), read_root(), set_full_compaction(), and write_block().

The documentation for this class was generated from the following files:

backends/flint/flint_table.h
backends/flint/flint_table.cc


Public Member Functions
	FlintTable (const char *tablename_, const std::string &path_, bool readonly_, int compress_strategy_=DONT_COMPRESS, bool lazy=false)
	Create a new Btree object.
	~FlintTable ()
	Close the Btree.
void	close (bool permanent=false)
	Close the Btree.
bool	exists () const
	Determine whether the btree exists on disk.
void	open ()
	Open the btree at the latest revision.
bool	open (flint_revision_number_t revision_)
	Open the btree at a given revision.
void	flush_db ()
	Flush any outstanding changes to the DB file of the table.
void	commit (flint_revision_number_t revision, int changes_fd=-1, const std::string *changes_tail=NULL)
	Commit any outstanding changes to the table.
void	write_changed_blocks (int changes_fd)
	Append the list of blocks changed to a changeset file.
void	cancel ()
	Cancel any outstanding changes.
bool	get_exact_entry (const std::string &key, std::string &tag) const
	Read an entry from the table, if and only if it is exactly that being asked for.
bool	key_exists (const std::string &key) const
	Check if a key exists in the Btree.
bool	read_tag (Cursor_ C_, std::string tag, bool keep_compressed) const
	Read the tag value for the key pointed to by cursor C_.
void	add (const std::string &key, std::string tag, bool already_compressed=false)
	Add a key/tag pair to the table, replacing any existing pair with the same key.
bool	del (const std::string &key)
	Delete an entry from the table.
void	erase ()
	Erase this table from disk.
void	set_block_size (unsigned int block_size_)
	Set the block size.
unsigned int	get_block_size () const
	Get the block size.
void	create_and_open (unsigned int blocksize)
	Create a new empty btree structure on disk and open it at the initial revision.
void	set_full_compaction (bool parity)
flint_revision_number_t	get_latest_revision_number () const
	Get the latest revision number stored in this table.
flint_revision_number_t	get_open_revision_number () const
	Get the revision number at which this table is currently open.
flint_tablesize_t	get_entry_count () const
	Return a count of the number of entries in the table.
bool	empty () const
	Return true if there are no entries in the table.
FlintCursor *	cursor_get () const
	Get a cursor for reading from the table.
bool	is_modified () const
	Determine whether the object contains uncommitted modifications.
void	set_max_item_size (size_t block_capacity)
	Set the maximum item size given the block capacity.
Protected Member Functions
bool	do_open_to_read (bool revision_supplied, flint_revision_number_t revision_)
	Perform the opening operation to read.
bool	do_open_to_write (bool revision_supplied, flint_revision_number_t revision_, bool create_db=false)
	Perform the opening operation to write.
bool	basic_open (bool revision_supplied, flint_revision_number_t revision)
bool	find (Cursor_ *) const
	find(C_) searches for the key of B->kt in the B-tree.
int	delete_kt ()
void	read_block (uint4 n, byte *p) const
	read_block(n, p) reads block n of the DB file to address p.
void	write_block (uint4 n, const byte *p) const
	write_block(n, p) writes block n in the DB file from address p.
	XAPIAN_NORETURN (void set_overwritten() const)
void	block_to_cursor (Cursor_ *C_, int j, uint4 n) const
void	alter ()
	Btree::alter(); is called when the B-tree is to be altered.
void	compact (byte *p)
	compact(p) compact the block at p by shuffling all the items up to the end.
void	enter_key (int j, Key_ prevkey, Key_ newkey)
	enter_key(j, prevkey, newkey) is called after a block split.
int	mid_point (byte *p)
	mid_point(p) finds the directory entry in c that determines the approximate mid point of the data in the block at p.
void	add_item_to_block (byte *p, Item_wr_ kt, int c)
	add_item_to_block(p, kt_, c) adds item kt_ to the block at p.
void	add_item (Item_wr_ kt, int j)
	FlintTable::add_item(kt_, j) adds item kt_ to the block at cursor level C[j].
void	delete_item (int j, bool repeatedly)
	FlintTable::delete_item(j, repeatedly) is (almost) the converse of add_item.
int	add_kt (bool found)
	add_kt(found) adds the item (key-tag pair) at B->kt into the B-tree, using cursor C.
void	read_root ()
void	split_root (uint4 split_n)
	Btree needs to gain a new level to insert more items: so split root block and construct a new one.
void	form_key (const std::string &key) const
char	other_base_letter () const
void	lazy_alloc_deflate_zstream () const
	Allocate the zstream for deflating, if not already allocated.
void	lazy_alloc_inflate_zstream () const
	Allocate the zstream for inflating, if not already allocated.
bool	prev (Cursor_ *C_, int j) const
bool	next (Cursor_ *C_, int j) const
bool	prev_default (Cursor_ *C_, int j) const
bool	next_default (Cursor_ *C_, int j) const
bool	prev_for_sequential (Cursor_ *C_, int dummy) const
bool	next_for_sequential (Cursor_ *C_, int dummy) const
	XAPIAN_NORETURN (static void throw_database_closed())
	Throw an exception indicating that the database is closed.
Static Protected Member Functions
static int	find_in_block (const byte *p, Key_ key, bool leaf, int c)
	find_in_block(p, key, leaf, c) searches for the key in the block at p.
static uint4	block_given_by (const byte *p, int c)
	block_given_by(p, c) finds the item at block address p, directory offset c, and returns its tag value as an integer.
Protected Attributes
const char *	tablename
	The name of the table (used when writing changesets).
flint_revision_number_t	revision_number
	revision number of the opened B-tree.
uint4	item_count
	keeps a count of the number of items in the B-tree.
unsigned int	block_size
	block size of the B tree in bytes
flint_revision_number_t	latest_revision_number
	Revision number of the other base, or zero if there is only one base file.
bool	both_bases
	set to true if baseA and baseB both exist as valid bases.
char	base_letter
	the value 'A' or 'B' of the current base
bool	faked_root_block
	true if the root block is faked (not written to disk).
bool	sequential
	true iff the data has been written in a single write in sequential order.
int	handle
	corresponding file handle
int	level
	number of levels, counting from 0
uint4	root
	the root block of the B-tree
Item_wr_	kt
	buffer of size block_size for making up key-tag items
byte *	buffer
	buffer of size block_size for reforming blocks
FlintTable_base	base
	For writing back as file baseA or baseB.
std::string	name
	The path name of the B tree.
int	seq_count
	count of the number of successive instances of purely sequential addition, starting at SEQ_START_POINT (neg) and going up to zero.
uint4	changed_n
	the last block to be changed by an addition
int	changed_c
	directory offset corresponding to last block to be changed by an addition
size_t	max_item_size
	maximum size of an item (key-tag pair)
bool	Btree_modified
	Set to true the first time the B-tree is modified.
bool	full_compaction
	set to true when full compaction is to be achieved
bool	writable
	Set to true when the database is opened to write.
bool	cursor_created_since_last_modification
	Flag for tracking when cursors need to rebuild.
unsigned long	cursor_version
	Version count for tracking when cursors need to rebuild.
Cursor_	C [BTREE_CURSOR_LEVELS]
byte *	split_p
	Buffer used when splitting a block.
int	compress_strategy
	DONT_COMPRESS or Z_DEFAULT_STRATEGY, Z_FILTERED, Z_HUFFMAN_ONLY, Z_RLE.
z_stream *	deflate_zstream
	Zlib state object for deflating.
z_stream *	inflate_zstream
	Zlib state object for inflating.
bool	lazy
	If true, don't create the table until it's needed.
Private Member Functions
	FlintTable (const FlintTable &)
	Copying not allowed.
FlintTable &	operator= (const FlintTable &)
	Assignment not allowed.
bool	really_empty () const
	Return true if there are no entries in the table.
Friends
class	FlintCursor