database/sqlite
1
0
Fork 0
mirror of https://github.com/sqlite/sqlite.git synced 2026-01-06 08:01:16 +03:00
Code Activity

Updates to the sqlite3_pcache_methods documentation.

Browse Source 
FossilOrigin-Name: b21425c4045883fffa46af632e77cf708d862927
This commit is contained in:
drh
2010-09-09 15:48:20 +00:00
parent 7413847759
commit cee8296af2
3 changed files with 61 additions and 37 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
manifest
View File

@@ -1,5 +1,8 @@
C Add\sWHERE\sclause\stests\sto\se_select.test.
D 2010-09-09T11:33:09
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
C Updates\sto\sthe\ssqlite3_pcache_methods\sdocumentation.
D 2010-09-09T15:48:21
F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
F Makefile.in c599a15d268b1db2aeadea19df2adc3bf2eb6bee
F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -174,7 +177,7 @@ F src/resolve.c 1c0f32b64f8e3f555fe1f732f9d6f501a7f05706
F src/rowset.c 69afa95a97c524ba6faf3805e717b5b7ae85a697
F src/select.c b0b124781474e4e0c8f64022875e5e2009e13443
F src/shell.c 8517fc1f9c59ae4007e6cc8b9af91ab231ea2056
F src/sqlite.h.in 0e98e780993e6cf185bd228f275b959a5aef86c6
F src/sqlite.h.in b89e75082482613994267333e7c0be1b5e33a788
F src/sqlite3ext.h 69dfb8116af51b84a029cddb3b35062354270c89
F src/sqliteInt.h 81343db96497aebf81dff9c695dfd29699b377b3
F src/sqliteLimit.h a17dcd3fb775d63b64a43a55c54cb282f9726f44
@@ -857,7 +860,14 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
P 2c6b1ca952be9979b8079431c2abad28419b6256
R b6f7deab8c7be4f26ac3335bb0b04fd4
U dan
Z 4c41231d0dc68008d74e0f7cc7244851
P 721b73fa5c5898f6c6d5946e1c70ccd2d0b0dccc
R cbbf9e5140816a6f83795c0332dd3e6e
U drh
Z 74027c69905e1ff505b64e9812591b2f
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.6 (GNU/Linux)
iD8DBQFMiQHJoxKgR168RlERAh0tAJ9SNKXu692V3wFNhD4OrbnaYo0azACfaJuF
JHEOkaCKu3GeiSh9DjF/ixg=
=IXg9
-----END PGP SIGNATURE-----

2
manifest.uuid
View File

@@ -1 +1 @@
721b73fa5c5898f6c6d5946e1c70ccd2d0b0dccc
b21425c4045883fffa46af632e77cf708d862927

72
src/sqlite.h.in
View File

@@ -4948,7 +4948,7 @@ void sqlite3_mutex_leave(sqlite3_mutex*);
**
** ^The xMutexInit method defined by this structure is invoked as
** part of system initialization by the sqlite3_initialize() function.
** ^The xMutexInit routine is calle by SQLite exactly once for each
** ^The xMutexInit routine is called by SQLite exactly once for each
** effective call to [sqlite3_initialize()].
**
** ^The xMutexEnd method defined by this structure is invoked as
@@ -5416,32 +5416,42 @@ typedef struct sqlite3_pcache sqlite3_pcache;
**
** ^(The [sqlite3_config]([SQLITE_CONFIG_PCACHE], ...) interface can
** register an alternative page cache implementation by passing in an
** instance of the sqlite3_pcache_methods structure.)^ The majority of the
** heap memory used by SQLite is used by the page cache to cache data read
** from, or ready to be written to, the database file. By implementing a
** custom page cache using this API, an application can control more
** precisely the amount of memory consumed by SQLite, the way in which
** instance of the sqlite3_pcache_methods structure.)^
** In many applications, most of the heap memory allocated by
** SQLite is used for the page cache.
** By implementing a
** custom page cache using this API, an application can better control
** the amount of memory consumed by SQLite, the way in which
** that memory is allocated and released, and the policies used to
** determine exactly which parts of a database file are cached and for
** how long.
**
** The alternative page cache mechanism is an
** extreme measure that is only needed by the most demanding applications.
** The built-in page cache is recommended for most uses.
**
** ^(The contents of the sqlite3_pcache_methods structure are copied to an
** internal buffer by SQLite within the call to [sqlite3_config]. Hence
** the application may discard the parameter after the call to
** [sqlite3_config()] returns.)^
**
** ^The xInit() method is called once for each call to [sqlite3_initialize()]
** ^(The xInit() method is called once for each effective
** call to [sqlite3_initialize()])^
** (usually only once during the lifetime of the process). ^(The xInit()
** method is passed a copy of the sqlite3_pcache_methods.pArg value.)^
** ^The xInit() method can set up up global structures and/or any mutexes
** The intent of the xInit() method is to set up global data structures
** required by the custom page cache implementation.
** ^(If the xInit() method is NULL, then the call to
** [sqlite3_config]([SQLITE_CONFIG_PCACHE],...) will install the
** built-in default page cache.)^
**
** ^The xShutdown() method is called from within [sqlite3_shutdown()],
** if the application invokes this API. It can be used to clean up
** ^The xShutdown() method is called by [sqlite3_shutdown()].
** It can be used to clean up
** any outstanding resources before process shutdown, if required.
** ^The xShutdown() method may be NULL.
**
** ^SQLite holds a [SQLITE_MUTEX_RECURSIVE] mutex when it invokes
** the xInit method, so the xInit method need not be threadsafe. ^The
** ^SQLite automatically serializes calls to the xInit method,
** so the xInit method need not be threadsafe. ^The
** xShutdown method is only called from [sqlite3_shutdown()] so it does
** not need to be threadsafe either. All other methods must be threadsafe
** in multithreaded applications.
@@ -5449,40 +5459,43 @@ typedef struct sqlite3_pcache sqlite3_pcache;
** ^SQLite will never invoke xInit() more than once without an intervening
** call to xShutdown().
**
** ^The xCreate() method is used to construct a new cache instance. SQLite
** will typically create one cache instance for each open database file,
** ^SQLite invokes the xCreate() method to construct a new cache instance.
** SQLite will typically create one cache instance for each open database file,
** though this is not guaranteed. ^The
** first parameter, szPage, is the size in bytes of the pages that must
** be allocated by the cache. ^szPage will not be a power of two. ^szPage
** will the page size of the database file that is to be cached plus an
** increment (here called "R") of about 100 or 200. ^SQLite will use the
** increment (here called "R") of about 100 or 200. SQLite will use the
** extra R bytes on each page to store metadata about the underlying
** database page on disk. The value of R depends
** on the SQLite version, the target platform, and how SQLite was compiled.
** ^R is constant for a particular build of SQLite. ^The second argument to
** xCreate(), bPurgeable, is true if the cache being created will
** be used to cache database pages of a file stored on disk, or
** false if it is used for an in-memory database. ^The cache implementation
** false if it is used for an in-memory database. The cache implementation
** does not have to do anything special based with the value of bPurgeable;
** it is purely advisory. ^On a cache where bPurgeable is false, SQLite will
** never invoke xUnpin() except to deliberately delete a page.
** ^In other words, a cache created with bPurgeable set to false will
** ^In other words, calls to xUnpin() on a cache with bPurgeable set to
** false will always have the "discard" flag set to true.
** ^Hence, a cache created with bPurgeable false will
** never contain any unpinned pages.
**
** ^(The xCachesize() method may be called at any time by SQLite to set the
** suggested maximum cache-size (number of pages stored by) the cache
** instance passed as the first argument. This is the value configured using
** the SQLite "[PRAGMA cache_size]" command.)^ ^As with the bPurgeable
** the SQLite "[PRAGMA cache_size]" command.)^ As with the bPurgeable
** parameter, the implementation is not required to do anything with this
** value; it is advisory only.
**
** ^The xPagecount() method should return the number of pages currently
** stored in the cache.
** ^The xPagecount() method must return the number of pages currently
** stored in the cache, both pinned and unpinned.
**
** ^The xFetch() method is used to fetch a page and return a pointer to it.
** ^The xFetch() method locates a page in the cache and returns a pointer to
** the page, or a NULL pointer.
** ^A 'page', in this context, is a buffer of szPage bytes aligned at an
** 8-byte boundary. ^The page to be fetched is determined by the key. ^The
** mimimum key value is 1. After it has been retrieved using xFetch, the page
** mimimum key value is 1. ^After it has been retrieved using xFetch, the page
** is considered to be "pinned".
**
** ^If the requested page is already in the page cache, then the page cache
@@ -5501,27 +5514,28 @@ typedef struct sqlite3_pcache sqlite3_pcache;
** </table>)^
**
** SQLite will normally invoke xFetch() with a createFlag of 0 or 1. If
** a call to xFetch() with createFlag==1 returns NULL, then SQLite will
** a call to xFetch() with createFlag==1 returns NULL, then SQLite may
** attempt to unpin one or more cache pages by spilling the content of
** pinned pages to disk and synching the operating system disk cache. After
** attempting to unpin pages, the xFetch() method will be invoked again with
** attempting to unpin pages, the xFetch() method may be invoked again with
** a createFlag of 2.
**
** ^xUnpin() is called by SQLite with a pointer to a currently pinned page
** as its second argument. ^(If the third parameter, discard, is non-zero,
** then the page should be evicted from the cache. In this case SQLite
** assumes that the next time the page is retrieved from the cache using
** the xFetch() method, it will be zeroed.)^ ^If the discard parameter is
** zero, then the page is considered to be unpinned. ^The cache implementation
** the xFetch() method, it will be zeroed.)^ If the discard parameter is
** zero, then the page may be discarded or retained at the discretion of
** page cache implementation. The page cache implementation
** may choose to evict unpinned pages at any time.
**
** ^(The cache is not required to perform any reference counting. A single
** ^(The cache must not perform any reference counting. A single
** call to xUnpin() unpins the page regardless of the number of prior calls
** to xFetch().)^
**
** ^The xRekey() method is used to change the key value associated with the
** page passed as the second argument from oldKey to newKey. ^If the cache
** previously contains an entry associated with newKey, it should be
** page passed as the second argument. ^If the cache
** previously contains an entry associated with newKey, it must be
** discarded. ^Any prior cache entry associated with newKey is guaranteed not
** to be pinned.
**