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Allow virtual tables to be used in shared-cache mode. (CVS 6928)
FossilOrigin-Name: 5d9e767a05e381235e064061043e30cc03a11a07
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danielk1977
@@ -11,7 +11,7 @@
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*************************************************************************
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** Internal interface definitions for SQLite.
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**
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** @(#) $Id: sqliteInt.h,v 1.893 2009/07/13 15:52:38 drh Exp $
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** @(#) $Id: sqliteInt.h,v 1.894 2009/07/24 17:58:53 danielk1977 Exp $
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*/
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#ifndef _SQLITEINT_H_
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#define _SQLITEINT_H_
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@@ -613,6 +613,7 @@ typedef struct TriggerStack TriggerStack;
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typedef struct TriggerStep TriggerStep;
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typedef struct Trigger Trigger;
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typedef struct UnpackedRecord UnpackedRecord;
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typedef struct VTable VTable;
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typedef struct Walker Walker;
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typedef struct WherePlan WherePlan;
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typedef struct WhereInfo WhereInfo;
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@@ -839,8 +840,9 @@ struct sqlite3 {
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#ifndef SQLITE_OMIT_VIRTUALTABLE
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Hash aModule; /* populated by sqlite3_create_module() */
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Table *pVTab; /* vtab with active Connect/Create method */
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sqlite3_vtab **aVTrans; /* Virtual tables with open transactions */
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VTable **aVTrans; /* Virtual tables with open transactions */
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int nVTrans; /* Allocated size of aVTrans */
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VTable *pDisconnect; /* Disconnect these in next sqlite3_prepare() */
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#endif
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FuncDefHash aFunc; /* Hash table of connection functions */
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Hash aCollSeq; /* All collating sequences */
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@@ -905,7 +907,6 @@ struct sqlite3 {
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#define SQLITE_LoadExtension 0x00020000 /* Enable load_extension */
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#define SQLITE_RecoveryMode 0x00040000 /* Ignore schema errors */
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#define SQLITE_SharedCache 0x00080000 /* Cache sharing is enabled */
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#define SQLITE_ReverseOrder 0x00100000 /* Reverse unordered SELECTs */
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/*
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@@ -1114,6 +1115,56 @@ struct CollSeq {
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#define SQLITE_JUMPIFNULL 0x08 /* jumps if either operand is NULL */
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#define SQLITE_STOREP2 0x10 /* Store result in reg[P2] rather than jump */
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/*
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** An object of this type is created for each virtual table present in
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** the database schema.
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**
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** If the database schema is shared, then there is one instance of this
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** structure for each database connection (sqlite3*) that uses the shared
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** schema. This is because each database connection requires its own unique
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** instance of the sqlite3_vtab* handle used to access the virtual table
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** implementation. sqlite3_vtab* handles can not be shared between
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** database connections, even when the rest of the in-memory database
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** schema is shared, as the implementation often stores the database
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** connection handle passed to it via the xConnect() or xCreate() method
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** during initialization internally. This database connection handle may
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** then used by the virtual table implementation to access real tables
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** within the database. So that they appear as part of the callers
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** transaction, these accesses need to be made via the same database
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** connection as that used to execute SQL operations on the virtual table.
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**
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** All VTable objects that correspond to a single table in a shared
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** database schema are initially stored in a linked-list pointed to by
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** the Table.pVTable member variable of the corresponding Table object.
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** When an sqlite3_prepare() operation is required to access the virtual
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** table, it searches the list for the VTable that corresponds to the
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** database connection doing the preparing so as to use the correct
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** sqlite3_vtab* handle in the compiled query.
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**
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** When an in-memory Table object is deleted (for example when the
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** schema is being reloaded for some reason), the VTable objects are not
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** deleted and the sqlite3_vtab* handles are not xDisconnect()ed
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** immediately. Instead, they are moved from the Table.pVTable list to
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** another linked list headed by the sqlite3.pDisconnect member of the
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** corresponding sqlite3 structure. They are then deleted/xDisconnected
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** next time a statement is prepared using said sqlite3*. This is done
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** to avoid deadlock issues involving multiple sqlite3.mutex mutexes.
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** Refer to comments above function sqlite3VtabUnlockList() for an
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** explanation as to why it is safe to add an entry to an sqlite3.pDisconnect
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** list without holding the corresponding sqlite3.mutex mutex.
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**
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** The memory for objects of this type is always allocated by
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** sqlite3DbMalloc(), using the connection handle stored in VTable.db as
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** the first argument.
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*/
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struct VTable {
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sqlite3 *db; /* Database connection associated with this table */
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Module *pMod; /* Pointer to module implementation */
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sqlite3_vtab *pVtab; /* Pointer to vtab instance */
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int nRef; /* Number of pointers to this structure */
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VTable *pNext; /* Next in linked list (see above) */
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};
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/*
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** Each SQL table is represented in memory by an instance of the
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** following structure.
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@@ -1165,8 +1216,7 @@ struct Table {
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int addColOffset; /* Offset in CREATE TABLE stmt to add a new column */
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#endif
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#ifndef SQLITE_OMIT_VIRTUALTABLE
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Module *pMod; /* Pointer to the implementation of the module */
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sqlite3_vtab *pVtab; /* Pointer to the module instance */
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VTable *pVTable; /* List of VTable objects. */
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int nModuleArg; /* Number of arguments to the module */
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char **azModuleArg; /* Text of all module args. [0] is module name */
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#endif
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@@ -2812,21 +2862,25 @@ void sqlite3AutoLoadExtensions(sqlite3*);
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#endif
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#ifdef SQLITE_OMIT_VIRTUALTABLE
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# define sqlite3VtabClear(X)
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# define sqlite3VtabClear(Y)
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# define sqlite3VtabSync(X,Y) SQLITE_OK
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# define sqlite3VtabRollback(X)
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# define sqlite3VtabCommit(X)
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# define sqlite3VtabInSync(db) 0
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# define sqlite3VtabLock(X)
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# define sqlite3VtabUnlock(X)
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# define sqlite3VtabUnlockList(X)
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#else
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void sqlite3VtabClear(Table*);
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int sqlite3VtabSync(sqlite3 *db, char **);
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int sqlite3VtabRollback(sqlite3 *db);
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int sqlite3VtabCommit(sqlite3 *db);
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void sqlite3VtabLock(VTable *);
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void sqlite3VtabUnlock(VTable *);
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void sqlite3VtabUnlockList(sqlite3*);
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# define sqlite3VtabInSync(db) ((db)->nVTrans>0 && (db)->aVTrans==0)
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#endif
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void sqlite3VtabMakeWritable(Parse*,Table*);
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void sqlite3VtabLock(sqlite3_vtab*);
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void sqlite3VtabUnlock(sqlite3*, sqlite3_vtab*);
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void sqlite3VtabBeginParse(Parse*, Token*, Token*, Token*);
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void sqlite3VtabFinishParse(Parse*, Token*);
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void sqlite3VtabArgInit(Parse*);
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@@ -2834,7 +2888,7 @@ void sqlite3VtabArgExtend(Parse*, Token*);
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int sqlite3VtabCallCreate(sqlite3*, int, const char *, char **);
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int sqlite3VtabCallConnect(Parse*, Table*);
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int sqlite3VtabCallDestroy(sqlite3*, int, const char *);
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int sqlite3VtabBegin(sqlite3 *, sqlite3_vtab *);
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int sqlite3VtabBegin(sqlite3 *, VTable *);
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FuncDef *sqlite3VtabOverloadFunction(sqlite3 *,FuncDef*, int nArg, Expr*);
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void sqlite3InvalidFunction(sqlite3_context*,int,sqlite3_value**);
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int sqlite3TransferBindings(sqlite3_stmt *, sqlite3_stmt *);
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@@ -2842,6 +2896,7 @@ int sqlite3Reprepare(Vdbe*);
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void sqlite3ExprListCheckLength(Parse*, ExprList*, const char*);
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CollSeq *sqlite3BinaryCompareCollSeq(Parse *, Expr *, Expr *);
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int sqlite3TempInMemory(const sqlite3*);
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VTable *sqlite3GetVTable(sqlite3*, Table*);
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