Package org.tmatesoft.sqljet.core.internal.btree

Class SqlJetBtree

    • Constructor Detail

      • SqlJetBtree

        public SqlJetBtree()

    • Method Detail

      • invokeBusyHandler

        public boolean invokeBusyHandler​(int number)
        Invoke the busy handler for a btree.

      • enter

        public void enter()
        Description copied from interface: ISqlJetBtree
        Enter a mutex on the given BTree object. If the object is not sharable, then no mutex is ever required and this routine is a no-op. The underlying mutex is non-recursive. But we keep a reference count in Btree.wantToLock so the behavior of this interface is recursive. To avoid deadlocks, multiple Btrees are locked in the same order by all database connections. The p->pNext is a list of other Btrees belonging to the same database connection as the p Btree which need to be locked after p. If we cannot get a lock on p, then first unlock all of the others on p->pNext, then wait for the lock to become available on p, then relock all of the subsequent Btrees that desire a lock.
        Specified by:
        enter in interface ISqlJetBtree

      • leave

        public void leave()
        Description copied from interface: ISqlJetBtree
        Exit the recursive mutex on a Btree.
        Specified by:
        leave in interface ISqlJetBtree

      • open

        public void open​(java.io.File filename,
                 ISqlJetDbHandle db,
                 java.util.Set<SqlJetBtreeFlags> flags,
                 SqlJetFileType type,
                 java.util.Set<SqlJetFileOpenPermission> permissions)
          throws SqlJetException
        Description copied from interface: ISqlJetBtree
        Open a database file. zFilename is the name of the database file. If zFilename is NULL a new database with a random name is created. This randomly named database file will be deleted when sqlite3BtreeClose() is called. If zFilename is ":memory:" then an in-memory database is created that is automatically destroyed when it is closed.
        Specified by:
        open in interface ISqlJetBtree
        Parameters:
        filename - Name of database file to open
        db - Associated database connection
        flags - Flags
        Throws:
        SqlJetException

      • setCacheSize

        public void setCacheSize​(int mxPage)
        Description copied from interface: ISqlJetBtree
        Change the limit on the number of pages allowed in the cache. The maximum number of cache pages is set to the absolute value of mxPage. If mxPage is negative, the pager will operate asynchronously - it will not stop to do fsync()s to insure data is written to the disk surface before continuing. Transactions still work if synchronous is off, and the database cannot be corrupted if this program crashes. But if the operating system crashes or there is an abrupt power failure when synchronous is off, the database could be left in an inconsistent and unrecoverable state. Synchronous is on by default so database corruption is not normally a worry.
        Specified by:
        setCacheSize in interface ISqlJetBtree

      • setSafetyLevel

        public void setSafetyLevel​(SqlJetSafetyLevel level)
        Description copied from interface: ISqlJetBtree
        Change the way data is synced to disk in order to increase or decrease how well the database resists damage due to OS crashes and power failures. Level 1 is the same as asynchronous (no syncs() occur and there is a high probability of damage) Level 2 is the default. There is a very low but non-zero probability of damage. Level 3 reduces the probability of damage to near zero but with a write performance reduction.
        Specified by:
        setSafetyLevel in interface ISqlJetBtree

      • isSyncDisabled

        public boolean isSyncDisabled()
        Description copied from interface: ISqlJetBtree
        Return TRUE if the given btree is set to safety level 1. In other words, return TRUE if no sync() occurs on the disk files.
        Specified by:
        isSyncDisabled in interface ISqlJetBtree
        Returns:

      • setPageSize

        public void setPageSize​(int pageSize,
                        int reserve)
                 throws SqlJetException
        Description copied from interface: ISqlJetBtree
        Change the default pages size and the number of reserved bytes per page. The page size must be a power of 2 between 512 and 65536. If the page size supplied does not meet this constraint then the page size is not changed. Page sizes are constrained to be a power of two so that the region of the database file used for locking (beginning at PENDING_BYTE, the first byte past the 1GB boundary, 0x40000000) needs to occur at the beginning of a page. If parameter nReserve is less than zero, then the number of reserved bytes per page is left unchanged.
        Specified by:
        setPageSize in interface ISqlJetBtree
        Throws:
        SqlJetException

      • getPageSize

        public int getPageSize()
        Description copied from interface: ISqlJetBtree
        Return the currently defined page size
        Specified by:
        getPageSize in interface ISqlJetBtree
        Returns:

      • setMaxPageCount

        public void setMaxPageCount​(int mxPage)
                     throws SqlJetException
        Description copied from interface: ISqlJetBtree
        Set the maximum page count for a database if mxPage is positive. No changes are made if mxPage is 0 or negative. Regardless of the value of mxPage, return the maximum page count.
        Specified by:
        setMaxPageCount in interface ISqlJetBtree
        Throws:
        SqlJetException

      • setAutoVacuum

        public void setAutoVacuum​(SqlJetAutoVacuumMode autoVacuum)
                   throws SqlJetException
        Description copied from interface: ISqlJetBtree
        Change the 'auto-vacuum' property of the database. If the 'autoVacuum' parameter is non-zero, then auto-vacuum mode is enabled. If zero, it is disabled. The default value for the auto-vacuum property is determined by the SQLITE_DEFAULT_AUTOVACUUM macro.
        Specified by:
        setAutoVacuum in interface ISqlJetBtree
        Throws:
        SqlJetException

      • beginTrans

        public void beginTrans​(SqlJetTransactionMode mode)
                throws SqlJetException
        Description copied from interface: ISqlJetBtree
        Attempt to start a new transaction. A write-transaction is started if the second argument is nonzero, otherwise a read- transaction. If the second argument is 2 or more and exclusive transaction is started, meaning that no other process is allowed to access the database. A preexisting transaction may not be upgraded to exclusive by calling this routine a second time - the exclusivity flag only works for a new transaction. A write-transaction must be started before attempting any changes to the database. None of the following routines will work unless a transaction is started first: createTable() createIndex() clearTable() dropTable() insert() delete() updateMeta() If an initial attempt to acquire the lock fails because of lock contention and the database was previously unlocked, then invoke the busy handler if there is one. But if there was previously a read-lock, do not invoke the busy handler - just return BUSY. BUSY is returned when there is already a read-lock in order to avoid a deadlock. Suppose there are two processes A and B. A has a read lock and B has a reserved lock. B tries to promote to exclusive but is blocked because of A's read lock. A tries to promote to reserved but is blocked by B. One or the other of the two processes must give way or there can be no progress. By returning BUSY and not invoking the busy callback when A already has a read lock, we encourage A to give up and let B proceed.
        Specified by:
        beginTrans in interface ISqlJetBtree
        Throws:
        SqlJetException

      • commitPhaseOne

        public void commitPhaseOne​(java.lang.String master)
                    throws SqlJetException
        Description copied from interface: ISqlJetBtree
        This routine does the first phase of a two-phase commit. This routine causes a rollback journal to be created (if it does not already exist) and populated with enough information so that if a power loss occurs the database can be restored to its original state by playing back the journal. Then the contents of the journal are flushed out to the disk. After the journal is safely on oxide, the changes to the database are written into the database file and flushed to oxide. At the end of this call, the rollback journal still exists on the disk and we are still holding all locks, so the transaction has not committed. See sqlite3BtreeCommit() for the second phase of the commit process. This call is a no-op if no write-transaction is currently active on pBt. Otherwise, sync the database file for the btree pBt. zMaster points to the name of a master journal file that should be written into the individual journal file, or is NULL, indicating no master journal file (single database transaction). When this is called, the master journal should already have been created, populated with this journal pointer and synced to disk. Once this is routine has returned, the only thing required to commit the write-transaction for this database file is to delete the journal.
        Specified by:
        commitPhaseOne in interface ISqlJetBtree
        Throws:
        SqlJetException

      • commitPhaseTwo

        public void commitPhaseTwo()
                    throws SqlJetException
        Description copied from interface: ISqlJetBtree
        Commit the transaction currently in progress. This routine implements the second phase of a 2-phase commit. The sqlite3BtreeSync() routine does the first phase and should be invoked prior to calling this routine. The sqlite3BtreeSync() routine did all the work of writing information out to disk and flushing the contents so that they are written onto the disk platter. All this routine has to do is delete or truncate the rollback journal (which causes the transaction to commit) and drop locks. This will release the write lock on the database file. If there are no active cursors, it also releases the read lock.
        Specified by:
        commitPhaseTwo in interface ISqlJetBtree
        Throws:
        SqlJetException

      • rollback

        public void rollback()
              throws SqlJetException
        Description copied from interface: ISqlJetBtree
        Rollback the transaction in progress. All cursors will be invalided by this operation. Any attempt to use a cursor that was open at the beginning of this operation will result in an error. This will release the write lock on the database file. If there are no active cursors, it also releases the read lock.
        Specified by:
        rollback in interface ISqlJetBtree
        Throws:
        SqlJetException

      • beginStmt

        public void beginStmt()
               throws SqlJetException
        Description copied from interface: ISqlJetBtree
        Start a statement subtransaction. The subtransaction can can be rolled back independently of the main transaction. You must start a transaction before starting a subtransaction. The subtransaction is ended automatically if the main transaction commits or rolls back. Only one subtransaction may be active at a time. It is an error to try to start a new subtransaction if another subtransaction is already active. Statement subtransactions are used around individual SQL statements that are contained within a BEGIN...COMMIT block. If a constraint error occurs within the statement, the effect of that one statement can be rolled back without having to rollback the entire transaction.
        Specified by:
        beginStmt in interface ISqlJetBtree
        Throws:
        SqlJetException

      • rollbackStmt

        public void rollbackStmt()
                  throws SqlJetException
        Description copied from interface: ISqlJetBtree
        Rollback the active statement subtransaction. If no subtransaction is active this routine is a no-op. All cursors will be invalidated by this operation. Any attempt to use a cursor that was open at the beginning of this operation will result in an error.
        Specified by:
        rollbackStmt in interface ISqlJetBtree
        Throws:
        SqlJetException

      • pageReinit

        protected void pageReinit​(ISqlJetPage page)
                   throws SqlJetException
        During a rollback, when the pager reloads information into the cache so that the cache is restored to its original state at the start of the transaction, for each page restored this routine is called. This routine needs to reset the extra data section at the end of the page to agree with the restored data.
        Parameters:
        page -
        Throws:
        SqlJetException

      • createTable

        public int createTable​(java.util.Set<SqlJetBtreeTableCreateFlags> flags)
                throws SqlJetException
        Description copied from interface: ISqlJetBtree
        Create a new BTree table. Returns the page number for the root page of the new table. The type of type is determined by the flags parameter. Only the following values of flags are currently in use. Other values for flags might not work: INTKEY|LEAFDATA Used for SQL tables with rowid keys ZERODATA Used for SQL indices
        Specified by:
        createTable in interface ISqlJetBtree
        Returns:
        the page number for the root page of the new table
        Throws:
        SqlJetException

      • isInTrans

        public boolean isInTrans()
        Description copied from interface: ISqlJetBtree
        Return true if a transaction is active.
        Specified by:
        isInTrans in interface ISqlJetBtree
        Returns:

      • isInStmt

        public boolean isInStmt()
        Description copied from interface: ISqlJetBtree
        Return true if a statement transaction is active.
        Specified by:
        isInStmt in interface ISqlJetBtree
        Returns:

      • isInReadTrans

        public boolean isInReadTrans()
        Description copied from interface: ISqlJetBtree
        Return true if a read (or write) transaction is active.
        Specified by:
        isInReadTrans in interface ISqlJetBtree
        Returns:

      • getSchema

        public SqlJetSchema getSchema()
        Description copied from interface: ISqlJetBtree
        This function returns a pointer to a blob of memory associated with a single shared-btree. The memory is used by client code for its own purposes (for example, to store a high-level schema associated with the shared-btree).
        Specified by:
        getSchema in interface ISqlJetBtree
        Returns:

      • isSchemaLocked

        public boolean isSchemaLocked()
        Description copied from interface: ISqlJetBtree
        Return true if another user of the same shared btree as the argument handle holds an exclusive lock on the sqlite_master table.
        Specified by:
        isSchemaLocked in interface ISqlJetBtree
        Returns:

      • lockTable

        public void lockTable​(int table,
                      boolean isWriteLock)
        Description copied from interface: ISqlJetBtree
        Obtain a lock on the table whose root page is iTab. The lock is a write lock if isWritelock is true or a read lock if it is false.
        Specified by:
        lockTable in interface ISqlJetBtree

      • savepoint

        public void savepoint​(SqlJetSavepointOperation op,
                      int savepoint)
               throws SqlJetException
        Description copied from interface: ISqlJetBtree
        The second argument to this function, op, is always SAVEPOINT_ROLLBACK or SAVEPOINT_RELEASE. This function either releases or rolls back the savepoint identified by parameter iSavepoint, depending on the value of op. Normally, iSavepoint is greater than or equal to zero. However, if op is SAVEPOINT_ROLLBACK, then iSavepoint may also be -1. In this case the contents of the entire transaction are rolled back. This is different from a normal transaction rollback, as no locks are released and the transaction remains open.
        Specified by:
        savepoint in interface ISqlJetBtree
        Throws:
        SqlJetException

      • getFilename

        public java.io.File getFilename()
        Description copied from interface: ISqlJetBtree
        Return the full pathname of the underlying database file. The pager filename is invariant as long as the pager is open so it is safe to access without the BtShared mutex.
        Specified by:
        getFilename in interface ISqlJetBtree
        Returns:

      • getDirname

        public java.io.File getDirname()
        Description copied from interface: ISqlJetBtree
        Return the pathname of the directory that contains the database file. The pager directory name is invariant as long as the pager is open so it is safe to access without the BtShared mutex.
        Specified by:
        getDirname in interface ISqlJetBtree
        Returns:

      • getJournalname

        public java.io.File getJournalname()
        Description copied from interface: ISqlJetBtree
        Return the pathname of the journal file for this database. The return value of this routine is the same regardless of whether the journal file has been created or not. The pager journal filename is invariant as long as the pager is open so it is safe to access without the BtShared mutex.
        Specified by:
        getJournalname in interface ISqlJetBtree
        Returns:

      • copyFile

        public void copyFile​(ISqlJetBtree from)
              throws SqlJetException
        Description copied from interface: ISqlJetBtree
        Copy the complete content of from. A transaction must be active for both files. The size of file may be reduced by this operation. If anything goes wrong, the transaction is rolled back. If successful, commitPhaseOne() may be called before returning. The caller should finish committing the transaction by calling commit().
        Specified by:
        copyFile in interface ISqlJetBtree
        Throws:
        SqlJetException

      • incrVacuum

        public void incrVacuum()
                throws SqlJetException
        Description copied from interface: ISqlJetBtree
        A write-transaction must be opened before calling this function. It performs a single unit of work towards an incremental vacuum. If the incremental vacuum is finished after this function has run, DONE is thrown. If it is not finished, but no error occured, none isn't thrown. Otherwise an SQLite error code.
        Specified by:
        incrVacuum in interface ISqlJetBtree
        Throws:
        SqlJetException

      • dropTable

        public int dropTable​(int table)
              throws SqlJetException
        Description copied from interface: ISqlJetBtree
        Erase all information in a table and add the root of the table to the freelist. Except, the root of the principle table (the one on page 1) is never added to the freelist. This routine will fail with LOCKED if there are any open cursors on the table. If AUTOVACUUM is enabled and the page at table is not the last root page in the database file, then the last root page in the database file is moved into the slot formerly occupied by table and that last slot formerly occupied by the last root page is added to the freelist instead of iTable. In this say, all root pages are kept at the beginning of the database file, which is necessary for AUTOVACUUM to work right. Returned is the page number that used to be the last root page in the file before the move. If no page gets moved, returned is 0. The last root page is recorded in meta[3] and the value of meta[3] is updated by this procedure.
        Specified by:
        dropTable in interface ISqlJetBtree
        Returns:
        Throws:
        SqlJetException

      • clearTable

        public void clearTable​(int table,
                       int[] change)
                throws SqlJetException
        Description copied from interface: ISqlJetBtree
        Delete all information from a single table in the database. Table is the page number of the root of the table. After this routine returns, the root page is empty, but still exists. This routine will fail with LOCKED if there are any open read cursors on the table. Open write cursors are moved to the root of the table. If nChange is not NULL, then table table must be an intkey table. The integer value pointed to by nChange[0] is incremented by the number of entries in the table.
        Specified by:
        clearTable in interface ISqlJetBtree
        Throws:
        SqlJetException

      • getMeta

        public int getMeta​(int idx)
            throws SqlJetException
        Description copied from interface: ISqlJetBtree
        Read the meta-information out of a database file. Meta[0] is the number of free pages currently in the database. Meta[1] through meta[15] are available for use by higher layers. Meta[0] is read-only, the others are read/write. The schema layer numbers meta values differently. At the schema layer (and the SetCookie and ReadCookie opcodes) the number of free pages is not visible. So Cookie[0] is the same as Meta[1].
        Specified by:
        getMeta in interface ISqlJetBtree
        Returns:
        Throws:
        SqlJetException

      • tripAllCursors

        public void tripAllCursors​(SqlJetErrorCode errCode)
                    throws SqlJetException
        Description copied from interface: ISqlJetBtree
        This routine sets the state to CURSOR_FAULT and the error code to errCode for every cursor on BtShared that pBtree references. Every cursor is tripped, including cursors that belong to other database connections that happen to be sharing the cache with pBtree. This routine gets called when a rollback occurs. All cursors using the same cache must be tripped to prevent them from trying to use the btree after the rollback. The rollback may have deleted tables or moved root pages, so it is not sufficient to save the state of the cursor. The cursor must be invalidated.
        Specified by:
        tripAllCursors in interface ISqlJetBtree
        Throws:
        SqlJetException

      • getPager

        public ISqlJetPager getPager()
        Description copied from interface: ISqlJetBtree
        Return the pager associated with a BTree. This routine is used for testing and debugging only.
        Specified by:
        getPager in interface ISqlJetBtree
        Returns:

      • getCursor

        public ISqlJetBtreeCursor getCursor​(int table,
                                    boolean wrFlag,
                                    ISqlJetKeyInfo keyInfo)
                             throws SqlJetException
        Description copied from interface: ISqlJetBtree
        Create a new cursor for the BTree whose root is on the page iTable. The act of acquiring a cursor gets a read lock on the database file. If wrFlag==0, then the cursor can only be used for reading. If wrFlag==1, then the cursor can be used for reading or for writing if other conditions for writing are also met. These are the conditions that must be met in order for writing to be allowed: 1: The cursor must have been opened with wrFlag==1 2: Other database connections that share the same pager cache but which are not in the READ_UNCOMMITTED state may not have cursors open with wrFlag==0 on the same table. Otherwise the changes made by this write cursor would be visible to the read cursors in the other database connection. 3: The database must be writable (not on read-only media) 4: There must be an active transaction. No checking is done to make sure that page iTable really is the root page of a b-tree. If it is not, then the cursor acquired will not work correctly. It is assumed that the sqlite3BtreeCursorSize() bytes of memory pointed to by pCur have been zeroed by the caller.
        Specified by:
        getCursor in interface ISqlJetBtree
        Parameters:
        table - Index of root page
        wrFlag - true for writing. false for read-only
        keyInfo - First argument to compare function
        Returns:
        Throws:
        SqlJetException

      • integrityCheck

        public java.lang.String integrityCheck​(int[] root,
                                       int root2,
                                       int mxErr,
                                       int[] err)
        Description copied from interface: ISqlJetBtree
        This routine does a complete check of the given BTree file. aRoot[] is an array of pages numbers were each page number is the root page of a table. nRoot is the number of entries in aRoot. Write the number of error seen in nErr[0]. Except for some memory allocation errors, an error message held in memory obtained from malloc is returned if nErr[0] is non-zero. If nErr[0]==0 then NULL is returned. If a memory allocation error occurs, NULL is returned.
        Specified by:
        integrityCheck in interface ISqlJetBtree
        Returns: