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diff --git a/ext/rbu/sqlite3rbu.h b/ext/rbu/sqlite3rbu.h new file mode 100644 index 0000000..d156b31 --- /dev/null +++ b/ext/rbu/sqlite3rbu.h @@ -0,0 +1,633 @@ +/* +** 2014 August 30 +** +** The author disclaims copyright to this source code. In place of +** a legal notice, here is a blessing: +** +** May you do good and not evil. +** May you find forgiveness for yourself and forgive others. +** May you share freely, never taking more than you give. +** +************************************************************************* +** +** This file contains the public interface for the RBU extension. +*/ + +/* +** SUMMARY +** +** Writing a transaction containing a large number of operations on +** b-tree indexes that are collectively larger than the available cache +** memory can be very inefficient. +** +** The problem is that in order to update a b-tree, the leaf page (at least) +** containing the entry being inserted or deleted must be modified. If the +** working set of leaves is larger than the available cache memory, then a +** single leaf that is modified more than once as part of the transaction +** may be loaded from or written to the persistent media multiple times. +** Additionally, because the index updates are likely to be applied in +** random order, access to pages within the database is also likely to be in +** random order, which is itself quite inefficient. +** +** One way to improve the situation is to sort the operations on each index +** by index key before applying them to the b-tree. This leads to an IO +** pattern that resembles a single linear scan through the index b-tree, +** and all but guarantees each modified leaf page is loaded and stored +** exactly once. SQLite uses this trick to improve the performance of +** CREATE INDEX commands. This extension allows it to be used to improve +** the performance of large transactions on existing databases. +** +** Additionally, this extension allows the work involved in writing the +** large transaction to be broken down into sub-transactions performed +** sequentially by separate processes. This is useful if the system cannot +** guarantee that a single update process will run for long enough to apply +** the entire update, for example because the update is being applied on a +** mobile device that is frequently rebooted. Even after the writer process +** has committed one or more sub-transactions, other database clients continue +** to read from the original database snapshot. In other words, partially +** applied transactions are not visible to other clients. +** +** "RBU" stands for "Resumable Bulk Update". As in a large database update +** transmitted via a wireless network to a mobile device. A transaction +** applied using this extension is hence refered to as an "RBU update". +** +** +** LIMITATIONS +** +** An "RBU update" transaction is subject to the following limitations: +** +** * The transaction must consist of INSERT, UPDATE and DELETE operations +** only. +** +** * INSERT statements may not use any default values. +** +** * UPDATE and DELETE statements must identify their target rows by +** non-NULL PRIMARY KEY values. Rows with NULL values stored in PRIMARY +** KEY fields may not be updated or deleted. If the table being written +** has no PRIMARY KEY, affected rows must be identified by rowid. +** +** * UPDATE statements may not modify PRIMARY KEY columns. +** +** * No triggers will be fired. +** +** * No foreign key violations are detected or reported. +** +** * CHECK constraints are not enforced. +** +** * No constraint handling mode except for "OR ROLLBACK" is supported. +** +** +** PREPARATION +** +** An "RBU update" is stored as a separate SQLite database. A database +** containing an RBU update is an "RBU database". For each table in the +** target database to be updated, the RBU database should contain a table +** named "data_<target name>" containing the same set of columns as the +** target table, and one more - "rbu_control". The data_% table should +** have no PRIMARY KEY or UNIQUE constraints, but each column should have +** the same type as the corresponding column in the target database. +** The "rbu_control" column should have no type at all. For example, if +** the target database contains: +** +** CREATE TABLE t1(a INTEGER PRIMARY KEY, b TEXT, c UNIQUE); +** +** Then the RBU database should contain: +** +** CREATE TABLE data_t1(a INTEGER, b TEXT, c, rbu_control); +** +** The order of the columns in the data_% table does not matter. +** +** Instead of a regular table, the RBU database may also contain virtual +** tables or views named using the data_<target> naming scheme. +** +** Instead of the plain data_<target> naming scheme, RBU database tables +** may also be named data<integer>_<target>, where <integer> is any sequence +** of zero or more numeric characters (0-9). This can be significant because +** tables within the RBU database are always processed in order sorted by +** name. By judicious selection of the <integer> portion of the names +** of the RBU tables the user can therefore control the order in which they +** are processed. This can be useful, for example, to ensure that "external +** content" FTS4 tables are updated before their underlying content tables. +** +** If the target database table is a virtual table or a table that has no +** PRIMARY KEY declaration, the data_% table must also contain a column +** named "rbu_rowid". This column is mapped to the table's implicit primary +** key column - "rowid". Virtual tables for which the "rowid" column does +** not function like a primary key value cannot be updated using RBU. For +** example, if the target db contains either of the following: +** +** CREATE VIRTUAL TABLE x1 USING fts3(a, b); +** CREATE TABLE x1(a, b) +** +** then the RBU database should contain: +** +** CREATE TABLE data_x1(a, b, rbu_rowid, rbu_control); +** +** All non-hidden columns (i.e. all columns matched by "SELECT *") of the +** target table must be present in the input table. For virtual tables, +** hidden columns are optional - they are updated by RBU if present in +** the input table, or not otherwise. For example, to write to an fts4 +** table with a hidden languageid column such as: +** +** CREATE VIRTUAL TABLE ft1 USING fts4(a, b, languageid='langid'); +** +** Either of the following input table schemas may be used: +** +** CREATE TABLE data_ft1(a, b, langid, rbu_rowid, rbu_control); +** CREATE TABLE data_ft1(a, b, rbu_rowid, rbu_control); +** +** For each row to INSERT into the target database as part of the RBU +** update, the corresponding data_% table should contain a single record +** with the "rbu_control" column set to contain integer value 0. The +** other columns should be set to the values that make up the new record +** to insert. +** +** If the target database table has an INTEGER PRIMARY KEY, it is not +** possible to insert a NULL value into the IPK column. Attempting to +** do so results in an SQLITE_MISMATCH error. +** +** For each row to DELETE from the target database as part of the RBU +** update, the corresponding data_% table should contain a single record +** with the "rbu_control" column set to contain integer value 1. The +** real primary key values of the row to delete should be stored in the +** corresponding columns of the data_% table. The values stored in the +** other columns are not used. +** +** For each row to UPDATE from the target database as part of the RBU +** update, the corresponding data_% table should contain a single record +** with the "rbu_control" column set to contain a value of type text. +** The real primary key values identifying the row to update should be +** stored in the corresponding columns of the data_% table row, as should +** the new values of all columns being update. The text value in the +** "rbu_control" column must contain the same number of characters as +** there are columns in the target database table, and must consist entirely +** of 'x' and '.' characters (or in some special cases 'd' - see below). For +** each column that is being updated, the corresponding character is set to +** 'x'. For those that remain as they are, the corresponding character of the +** rbu_control value should be set to '.'. For example, given the tables +** above, the update statement: +** +** UPDATE t1 SET c = 'usa' WHERE a = 4; +** +** is represented by the data_t1 row created by: +** +** INSERT INTO data_t1(a, b, c, rbu_control) VALUES(4, NULL, 'usa', '..x'); +** +** Instead of an 'x' character, characters of the rbu_control value specified +** for UPDATEs may also be set to 'd'. In this case, instead of updating the +** target table with the value stored in the corresponding data_% column, the +** user-defined SQL function "rbu_delta()" is invoked and the result stored in +** the target table column. rbu_delta() is invoked with two arguments - the +** original value currently stored in the target table column and the +** value specified in the data_xxx table. +** +** For example, this row: +** +** INSERT INTO data_t1(a, b, c, rbu_control) VALUES(4, NULL, 'usa', '..d'); +** +** is similar to an UPDATE statement such as: +** +** UPDATE t1 SET c = rbu_delta(c, 'usa') WHERE a = 4; +** +** Finally, if an 'f' character appears in place of a 'd' or 's' in an +** ota_control string, the contents of the data_xxx table column is assumed +** to be a "fossil delta" - a patch to be applied to a blob value in the +** format used by the fossil source-code management system. In this case +** the existing value within the target database table must be of type BLOB. +** It is replaced by the result of applying the specified fossil delta to +** itself. +** +** If the target database table is a virtual table or a table with no PRIMARY +** KEY, the rbu_control value should not include a character corresponding +** to the rbu_rowid value. For example, this: +** +** INSERT INTO data_ft1(a, b, rbu_rowid, rbu_control) +** VALUES(NULL, 'usa', 12, '.x'); +** +** causes a result similar to: +** +** UPDATE ft1 SET b = 'usa' WHERE rowid = 12; +** +** The data_xxx tables themselves should have no PRIMARY KEY declarations. +** However, RBU is more efficient if reading the rows in from each data_xxx +** table in "rowid" order is roughly the same as reading them sorted by +** the PRIMARY KEY of the corresponding target database table. In other +** words, rows should be sorted using the destination table PRIMARY KEY +** fields before they are inserted into the data_xxx tables. +** +** USAGE +** +** The API declared below allows an application to apply an RBU update +** stored on disk to an existing target database. Essentially, the +** application: +** +** 1) Opens an RBU handle using the sqlite3rbu_open() function. +** +** 2) Registers any required virtual table modules with the database +** handle returned by sqlite3rbu_db(). Also, if required, register +** the rbu_delta() implementation. +** +** 3) Calls the sqlite3rbu_step() function one or more times on +** the new handle. Each call to sqlite3rbu_step() performs a single +** b-tree operation, so thousands of calls may be required to apply +** a complete update. +** +** 4) Calls sqlite3rbu_close() to close the RBU update handle. If +** sqlite3rbu_step() has been called enough times to completely +** apply the update to the target database, then the RBU database +** is marked as fully applied. Otherwise, the state of the RBU +** update application is saved in the RBU database for later +** resumption. +** +** See comments below for more detail on APIs. +** +** If an update is only partially applied to the target database by the +** time sqlite3rbu_close() is called, various state information is saved +** within the RBU database. This allows subsequent processes to automatically +** resume the RBU update from where it left off. +** +** To remove all RBU extension state information, returning an RBU database +** to its original contents, it is sufficient to drop all tables that begin +** with the prefix "rbu_" +** +** DATABASE LOCKING +** +** An RBU update may not be applied to a database in WAL mode. Attempting +** to do so is an error (SQLITE_ERROR). +** +** While an RBU handle is open, a SHARED lock may be held on the target +** database file. This means it is possible for other clients to read the +** database, but not to write it. +** +** If an RBU update is started and then suspended before it is completed, +** then an external client writes to the database, then attempting to resume +** the suspended RBU update is also an error (SQLITE_BUSY). +*/ + +#ifndef _SQLITE3RBU_H +#define _SQLITE3RBU_H + +#include "sqlite3.h" /* Required for error code definitions */ + +#ifdef __cplusplus +extern "C" { +#endif + +typedef struct sqlite3rbu sqlite3rbu; + +/* +** Open an RBU handle. +** +** Argument zTarget is the path to the target database. Argument zRbu is +** the path to the RBU database. Each call to this function must be matched +** by a call to sqlite3rbu_close(). When opening the databases, RBU passes +** the SQLITE_CONFIG_URI flag to sqlite3_open_v2(). So if either zTarget +** or zRbu begin with "file:", it will be interpreted as an SQLite +** database URI, not a regular file name. +** +** If the zState argument is passed a NULL value, the RBU extension stores +** the current state of the update (how many rows have been updated, which +** indexes are yet to be updated etc.) within the RBU database itself. This +** can be convenient, as it means that the RBU application does not need to +** organize removing a separate state file after the update is concluded. +** Or, if zState is non-NULL, it must be a path to a database file in which +** the RBU extension can store the state of the update. +** +** When resuming an RBU update, the zState argument must be passed the same +** value as when the RBU update was started. +** +** Once the RBU update is finished, the RBU extension does not +** automatically remove any zState database file, even if it created it. +** +** By default, RBU uses the default VFS to access the files on disk. To +** use a VFS other than the default, an SQLite "file:" URI containing a +** "vfs=..." option may be passed as the zTarget option. +** +** IMPORTANT NOTE FOR ZIPVFS USERS: The RBU extension works with all of +** SQLite's built-in VFSs, including the multiplexor VFS. However it does +** not work out of the box with zipvfs. Refer to the comment describing +** the zipvfs_create_vfs() API below for details on using RBU with zipvfs. +*/ +SQLITE_API sqlite3rbu *sqlite3rbu_open( + const char *zTarget, + const char *zRbu, + const char *zState +); + +/* +** Open an RBU handle to perform an RBU vacuum on database file zTarget. +** An RBU vacuum is similar to SQLite's built-in VACUUM command, except +** that it can be suspended and resumed like an RBU update. +** +** The second argument to this function identifies a database in which +** to store the state of the RBU vacuum operation if it is suspended. The +** first time sqlite3rbu_vacuum() is called, to start an RBU vacuum +** operation, the state database should either not exist or be empty +** (contain no tables). If an RBU vacuum is suspended by calling +** sqlite3rbu_close() on the RBU handle before sqlite3rbu_step() has +** returned SQLITE_DONE, the vacuum state is stored in the state database. +** The vacuum can be resumed by calling this function to open a new RBU +** handle specifying the same target and state databases. +** +** If the second argument passed to this function is NULL, then the +** name of the state database is "<database>-vacuum", where <database> +** is the name of the target database file. In this case, on UNIX, if the +** state database is not already present in the file-system, it is created +** with the same permissions as the target db is made. +** +** With an RBU vacuum, it is an SQLITE_MISUSE error if the name of the +** state database ends with "-vactmp". This name is reserved for internal +** use. +** +** This function does not delete the state database after an RBU vacuum +** is completed, even if it created it. However, if the call to +** sqlite3rbu_close() returns any value other than SQLITE_OK, the contents +** of the state tables within the state database are zeroed. This way, +** the next call to sqlite3rbu_vacuum() opens a handle that starts a +** new RBU vacuum operation. +** +** As with sqlite3rbu_open(), Zipvfs users should rever to the comment +** describing the sqlite3rbu_create_vfs() API function below for +** a description of the complications associated with using RBU with +** zipvfs databases. +*/ +SQLITE_API sqlite3rbu *sqlite3rbu_vacuum( + const char *zTarget, + const char *zState +); + +/* +** Configure a limit for the amount of temp space that may be used by +** the RBU handle passed as the first argument. The new limit is specified +** in bytes by the second parameter. If it is positive, the limit is updated. +** If the second parameter to this function is passed zero, then the limit +** is removed entirely. If the second parameter is negative, the limit is +** not modified (this is useful for querying the current limit). +** +** In all cases the returned value is the current limit in bytes (zero +** indicates unlimited). +** +** If the temp space limit is exceeded during operation, an SQLITE_FULL +** error is returned. +*/ +SQLITE_API sqlite3_int64 sqlite3rbu_temp_size_limit(sqlite3rbu*, sqlite3_int64); + +/* +** Return the current amount of temp file space, in bytes, currently used by +** the RBU handle passed as the only argument. +*/ +SQLITE_API sqlite3_int64 sqlite3rbu_temp_size(sqlite3rbu*); + +/* +** Internally, each RBU connection uses a separate SQLite database +** connection to access the target and rbu update databases. This +** API allows the application direct access to these database handles. +** +** The first argument passed to this function must be a valid, open, RBU +** handle. The second argument should be passed zero to access the target +** database handle, or non-zero to access the rbu update database handle. +** Accessing the underlying database handles may be useful in the +** following scenarios: +** +** * If any target tables are virtual tables, it may be necessary to +** call sqlite3_create_module() on the target database handle to +** register the required virtual table implementations. +** +** * If the data_xxx tables in the RBU source database are virtual +** tables, the application may need to call sqlite3_create_module() on +** the rbu update db handle to any required virtual table +** implementations. +** +** * If the application uses the "rbu_delta()" feature described above, +** it must use sqlite3_create_function() or similar to register the +** rbu_delta() implementation with the target database handle. +** +** If an error has occurred, either while opening or stepping the RBU object, +** this function may return NULL. The error code and message may be collected +** when sqlite3rbu_close() is called. +** +** Database handles returned by this function remain valid until the next +** call to any sqlite3rbu_xxx() function other than sqlite3rbu_db(). +*/ +SQLITE_API sqlite3 *sqlite3rbu_db(sqlite3rbu*, int bRbu); + +/* +** Do some work towards applying the RBU update to the target db. +** +** Return SQLITE_DONE if the update has been completely applied, or +** SQLITE_OK if no error occurs but there remains work to do to apply +** the RBU update. If an error does occur, some other error code is +** returned. +** +** Once a call to sqlite3rbu_step() has returned a value other than +** SQLITE_OK, all subsequent calls on the same RBU handle are no-ops +** that immediately return the same value. +*/ +SQLITE_API int sqlite3rbu_step(sqlite3rbu *pRbu); + +/* +** Force RBU to save its state to disk. +** +** If a power failure or application crash occurs during an update, following +** system recovery RBU may resume the update from the point at which the state +** was last saved. In other words, from the most recent successful call to +** sqlite3rbu_close() or this function. +** +** SQLITE_OK is returned if successful, or an SQLite error code otherwise. +*/ +SQLITE_API int sqlite3rbu_savestate(sqlite3rbu *pRbu); + +/* +** Close an RBU handle. +** +** If the RBU update has been completely applied, mark the RBU database +** as fully applied. Otherwise, assuming no error has occurred, save the +** current state of the RBU update appliation to the RBU database. +** +** If an error has already occurred as part of an sqlite3rbu_step() +** or sqlite3rbu_open() call, or if one occurs within this function, an +** SQLite error code is returned. Additionally, if pzErrmsg is not NULL, +** *pzErrmsg may be set to point to a buffer containing a utf-8 formatted +** English language error message. It is the responsibility of the caller to +** eventually free any such buffer using sqlite3_free(). +** +** Otherwise, if no error occurs, this function returns SQLITE_OK if the +** update has been partially applied, or SQLITE_DONE if it has been +** completely applied. +*/ +SQLITE_API int sqlite3rbu_close(sqlite3rbu *pRbu, char **pzErrmsg); + +/* +** Return the total number of key-value operations (inserts, deletes or +** updates) that have been performed on the target database since the +** current RBU update was started. +*/ +SQLITE_API sqlite3_int64 sqlite3rbu_progress(sqlite3rbu *pRbu); + +/* +** Obtain permyriadage (permyriadage is to 10000 as percentage is to 100) +** progress indications for the two stages of an RBU update. This API may +** be useful for driving GUI progress indicators and similar. +** +** An RBU update is divided into two stages: +** +** * Stage 1, in which changes are accumulated in an oal/wal file, and +** * Stage 2, in which the contents of the wal file are copied into the +** main database. +** +** The update is visible to non-RBU clients during stage 2. During stage 1 +** non-RBU reader clients may see the original database. +** +** If this API is called during stage 2 of the update, output variable +** (*pnOne) is set to 10000 to indicate that stage 1 has finished and (*pnTwo) +** to a value between 0 and 10000 to indicate the permyriadage progress of +** stage 2. A value of 5000 indicates that stage 2 is half finished, +** 9000 indicates that it is 90% finished, and so on. +** +** If this API is called during stage 1 of the update, output variable +** (*pnTwo) is set to 0 to indicate that stage 2 has not yet started. The +** value to which (*pnOne) is set depends on whether or not the RBU +** database contains an "rbu_count" table. The rbu_count table, if it +** exists, must contain the same columns as the following: +** +** CREATE TABLE rbu_count(tbl TEXT PRIMARY KEY, cnt INTEGER) WITHOUT ROWID; +** +** There must be one row in the table for each source (data_xxx) table within +** the RBU database. The 'tbl' column should contain the name of the source +** table. The 'cnt' column should contain the number of rows within the +** source table. +** +** If the rbu_count table is present and populated correctly and this +** API is called during stage 1, the *pnOne output variable is set to the +** permyriadage progress of the same stage. If the rbu_count table does +** not exist, then (*pnOne) is set to -1 during stage 1. If the rbu_count +** table exists but is not correctly populated, the value of the *pnOne +** output variable during stage 1 is undefined. +*/ +SQLITE_API void sqlite3rbu_bp_progress(sqlite3rbu *pRbu, int *pnOne, int*pnTwo); + +/* +** Obtain an indication as to the current stage of an RBU update or vacuum. +** This function always returns one of the SQLITE_RBU_STATE_XXX constants +** defined in this file. Return values should be interpreted as follows: +** +** SQLITE_RBU_STATE_OAL: +** RBU is currently building a *-oal file. The next call to sqlite3rbu_step() +** may either add further data to the *-oal file, or compute data that will +** be added by a subsequent call. +** +** SQLITE_RBU_STATE_MOVE: +** RBU has finished building the *-oal file. The next call to sqlite3rbu_step() +** will move the *-oal file to the equivalent *-wal path. If the current +** operation is an RBU update, then the updated version of the database +** file will become visible to ordinary SQLite clients following the next +** call to sqlite3rbu_step(). +** +** SQLITE_RBU_STATE_CHECKPOINT: +** RBU is currently performing an incremental checkpoint. The next call to +** sqlite3rbu_step() will copy a page of data from the *-wal file into +** the target database file. +** +** SQLITE_RBU_STATE_DONE: +** The RBU operation has finished. Any subsequent calls to sqlite3rbu_step() +** will immediately return SQLITE_DONE. +** +** SQLITE_RBU_STATE_ERROR: +** An error has occurred. Any subsequent calls to sqlite3rbu_step() will +** immediately return the SQLite error code associated with the error. +*/ +#define SQLITE_RBU_STATE_OAL 1 +#define SQLITE_RBU_STATE_MOVE 2 +#define SQLITE_RBU_STATE_CHECKPOINT 3 +#define SQLITE_RBU_STATE_DONE 4 +#define SQLITE_RBU_STATE_ERROR 5 + +SQLITE_API int sqlite3rbu_state(sqlite3rbu *pRbu); + +/* +** As part of applying an RBU update or performing an RBU vacuum operation, +** the system must at one point move the *-oal file to the equivalent *-wal +** path. Normally, it does this by invoking POSIX function rename(2) directly. +** Except on WINCE platforms, where it uses win32 API MoveFileW(). This +** function may be used to register a callback that the RBU module will invoke +** instead of one of these APIs. +** +** If a callback is registered with an RBU handle, it invokes it instead +** of rename(2) when it needs to move a file within the file-system. The +** first argument passed to the xRename() callback is a copy of the second +** argument (pArg) passed to this function. The second is the full path +** to the file to move and the third the full path to which it should be +** moved. The callback function should return SQLITE_OK to indicate +** success. If an error occurs, it should return an SQLite error code. +** In this case the RBU operation will be abandoned and the error returned +** to the RBU user. +** +** Passing a NULL pointer in place of the xRename argument to this function +** restores the default behaviour. +*/ +SQLITE_API void sqlite3rbu_rename_handler( + sqlite3rbu *pRbu, + void *pArg, + int (*xRename)(void *pArg, const char *zOld, const char *zNew) +); + + +/* +** Create an RBU VFS named zName that accesses the underlying file-system +** via existing VFS zParent. Or, if the zParent parameter is passed NULL, +** then the new RBU VFS uses the default system VFS to access the file-system. +** The new object is registered as a non-default VFS with SQLite before +** returning. +** +** Part of the RBU implementation uses a custom VFS object. Usually, this +** object is created and deleted automatically by RBU. +** +** The exception is for applications that also use zipvfs. In this case, +** the custom VFS must be explicitly created by the user before the RBU +** handle is opened. The RBU VFS should be installed so that the zipvfs +** VFS uses the RBU VFS, which in turn uses any other VFS layers in use +** (for example multiplexor) to access the file-system. For example, +** to assemble an RBU enabled VFS stack that uses both zipvfs and +** multiplexor (error checking omitted): +** +** // Create a VFS named "multiplex" (not the default). +** sqlite3_multiplex_initialize(0, 0); +** +** // Create an rbu VFS named "rbu" that uses multiplexor. If the +** // second argument were replaced with NULL, the "rbu" VFS would +** // access the file-system via the system default VFS, bypassing the +** // multiplexor. +** sqlite3rbu_create_vfs("rbu", "multiplex"); +** +** // Create a zipvfs VFS named "zipvfs" that uses rbu. +** zipvfs_create_vfs_v3("zipvfs", "rbu", 0, xCompressorAlgorithmDetector); +** +** // Make zipvfs the default VFS. +** sqlite3_vfs_register(sqlite3_vfs_find("zipvfs"), 1); +** +** Because the default VFS created above includes a RBU functionality, it +** may be used by RBU clients. Attempting to use RBU with a zipvfs VFS stack +** that does not include the RBU layer results in an error. +** +** The overhead of adding the "rbu" VFS to the system is negligible for +** non-RBU users. There is no harm in an application accessing the +** file-system via "rbu" all the time, even if it only uses RBU functionality +** occasionally. +*/ +SQLITE_API int sqlite3rbu_create_vfs(const char *zName, const char *zParent); + +/* +** Deregister and destroy an RBU vfs created by an earlier call to +** sqlite3rbu_create_vfs(). +** +** VFS objects are not reference counted. If a VFS object is destroyed +** before all database handles that use it have been closed, the results +** are undefined. +*/ +SQLITE_API void sqlite3rbu_destroy_vfs(const char *zName); + +#ifdef __cplusplus +} /* end of the 'extern "C"' block */ +#endif + +#endif /* _SQLITE3RBU_H */ |