// // $Id$ // // MCPStreamingResult.m // sequel-pro // // Created by Rowan Beentje on Aug 16, 2009 // Copyright 2009 Rowan Beentje. All rights reserved. // // This program is free software; you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation; either version 2 of the License, or // (at your option) any later version. // // This program is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // // You should have received a copy of the GNU General Public License // along with this program; if not, write to the Free Software // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA // // More info at <http://code.google.com/p/sequel-pro/> #import "MCPStreamingResult.h" #import "MCPConnection.h" #import "MCPNull.h" #import "MCPNumber.h" /** * IMPORTANT NOTE * * MCPStreamingResult can operate in two modes. The default mode is a safe implementation, * which operates in a multithreaded fashion - a worker thread is set up to download the results as * fast as possible in the background, while the results are made available via a blocking (and so * single-thread-compatible) fetchNextRowAsArray call. This provides the benefit of allowing a progress * bar to be shown during downloads, and threaded processing, but still has reasonable memory usage for * the downloaded result - and won't block the server. * Alternatively, withFullStreaming: can be set to YES, in which case each row will be accessed on-demand; * this can be dangerous as it means a SELECT will tie up the server for longer, as for MyISAM tables * updates (and subsequent reads) must block while a SELECT is still running. However this can be useful * for certain processes such as working with very large tables to keep memory usage low. */ @interface MCPStreamingResult (PrivateAPI) const char *_int2bin(unsigned int n, unsigned long len, char *buf); - (void) _downloadAllData; - (void) _freeAllDataWhenDone; @end @implementation MCPStreamingResult : MCPResult #pragma mark - #pragma mark Setup and teardown /** * Initialise a MCPStreamingResult in the same way as MCPResult - as used * internally by the MCPConnection !{queryString:} method. */ - (id)initWithMySQLPtr:(MYSQL *)mySQLPtr encoding:(NSStringEncoding)theEncoding timeZone:(NSTimeZone *)theTimeZone connection:(MCPConnection *)theConnection { return [self initWithMySQLPtr:mySQLPtr encoding:theEncoding timeZone:theTimeZone connection:theConnection withFullStreaming:NO]; } /** * Master initialisation method, allowing selection of either full streaming or safe streaming * (see "important note" above) */ - (id)initWithMySQLPtr:(MYSQL *)mySQLPtr encoding:(NSStringEncoding)theEncoding timeZone:(NSTimeZone *)theTimeZone connection:(MCPConnection *)theConnection withFullStreaming:(BOOL)useFullStreaming { if ((self = [super init])) { mEncoding = theEncoding; mTimeZone = [theTimeZone retain]; parentConnection = theConnection; fullyStreaming = useFullStreaming; connectionUnlocked = NO; if (mResult) { mysql_free_result(mResult); mResult = NULL; } if (mNames) { [mNames release]; mNames = nil; } mResult = mysql_use_result(mySQLPtr); if (mResult) { mNumOfFields = mysql_num_fields(mResult); fieldDefinitions = mysql_fetch_fields(mResult); } else { mNumOfFields = 0; } // Obtain SEL references and pointer isConnectedSEL = @selector(isConnected); isConnectedPtr = [parentConnection methodForSelector:isConnectedSEL]; // If the result is opened in download-data-fast safe mode, set up the additional variables // and threads required. if (!fullyStreaming) { dataDownloaded = NO; dataFreed = NO; localDataStore = NULL; currentDataStoreEntry = NULL; localDataStoreLastEntry = NULL; localDataRows = 0; localDataAllocated = 0; downloadedRowCount = 0; processedRowCount = 0; freedRowCount = 0; pthread_mutex_init(&dataCreationLock, NULL); pthread_mutex_init(&dataFreeLock, NULL); // Start the data download thread [NSThread detachNewThreadSelector:@selector(_downloadAllData) toTarget:self withObject:nil]; // Start the data freeing thread [NSThread detachNewThreadSelector:@selector(_freeAllDataWhenDone) toTarget:self withObject:nil]; } } return self; } /** * Deallocate the result and unlock the parent connection for further use */ - (void) dealloc { [self cancelResultLoad]; //this should close the connection if it is still open if (!connectionUnlocked) { //this should NEVER happen NSLog(@"MCPStreamingResult: The connection has not been unlocked."); [parentConnection unlockConnection]; } if (!fullyStreaming) { pthread_mutex_destroy(&dataFreeLock); pthread_mutex_destroy(&dataCreationLock); } [super dealloc]; } #pragma mark - #pragma mark Results fetching /** * Retrieve the next row of the result as an array. Should be called in a loop * until nil is returned to ensure all the results have been retrieved. */ - (NSArray *)fetchNextRowAsArray { MYSQL_ROW theRow; char *theRowData, *buf; unsigned long *fieldLengths; NSInteger i, copiedDataLength; NSMutableArray *returnArray; // Retrieve the next row according to the mode this result set is in. // If fully streaming, retrieve the MYSQL_ROW if (fullyStreaming) { theRow = mysql_fetch_row(mResult); // If no data was returned, we're at the end of the result set - unlock the connection and return nil if (theRow == NULL) { if (!connectionUnlocked) { [parentConnection unlockConnection]; connectionUnlocked = YES; } return nil; } // Retrieve the lengths of the returned data fieldLengths = mysql_fetch_lengths(mResult); // If in cached-streaming/fast download mode, get a reference to the data for the current row } else { copiedDataLength = 0; // Lock the data mutex pthread_mutex_lock(&dataCreationLock); // Check to see whether we need to wait for the data to be availabe // - if so, wait 1ms before checking again. while (!dataDownloaded && processedRowCount == downloadedRowCount) { pthread_mutex_unlock(&dataCreationLock); usleep(1000); pthread_mutex_lock(&dataCreationLock); } // If all rows have been processed, we're at the end of the result set - return nil // once all memory has been freed if (processedRowCount == downloadedRowCount) { pthread_mutex_unlock(&dataCreationLock); while (!dataFreed) usleep(1000); // Update the connection's error statuses in case of error during content download [parentConnection updateErrorStatuses]; return nil; } // Retrieve a reference to the data and the associated lengths theRowData = currentDataStoreEntry->data; fieldLengths = currentDataStoreEntry->dataLengths; // Unlock the data mutex pthread_mutex_unlock(&dataCreationLock); } // Initialise the array to return returnArray = [NSMutableArray arrayWithCapacity:mNumOfFields]; for (i = 0; i < mNumOfFields; i++) { id cellData = nil; char *theData = NULL; // In fully streaming mode, copy across the data for the MYSQL_ROW if (fullyStreaming) { if (theRow[i] == NULL) { cellData = [NSNull null]; } else { theData = calloc(sizeof(char), fieldLengths[i]+1); memcpy(theData, theRow[i], fieldLengths[i]); theData[fieldLengths[i]] = '\0'; } // In cached-streaming mode, use a reference to the downloaded data } else { if (fieldLengths[i] == NSNotFound) { cellData = [NSNull null]; } else { theData = theRowData+copiedDataLength; copiedDataLength += fieldLengths[i] + 1; } } // If the field is of type BIT, then allocate the binary buffer if (fieldDefinitions[i].type == FIELD_TYPE_BIT) { buf = malloc(fieldDefinitions[i].length + 1); } // If the data hasn't already been detected as NULL - in which case it will have been // set to NSNull - process the data by type if (cellData == nil) { switch (fieldDefinitions[i].type) { case FIELD_TYPE_TINY: case FIELD_TYPE_SHORT: case FIELD_TYPE_INT24: case FIELD_TYPE_LONG: case FIELD_TYPE_LONGLONG: case FIELD_TYPE_DECIMAL: case FIELD_TYPE_NEWDECIMAL: case FIELD_TYPE_FLOAT: case FIELD_TYPE_DOUBLE: case FIELD_TYPE_TIMESTAMP: case FIELD_TYPE_DATE: case FIELD_TYPE_TIME: case FIELD_TYPE_DATETIME: case FIELD_TYPE_YEAR: case FIELD_TYPE_VAR_STRING: case FIELD_TYPE_STRING: case FIELD_TYPE_SET: case FIELD_TYPE_ENUM: case FIELD_TYPE_NEWDATE: // Don't know what the format for this type is... // For fields of type BINARY/VARBINARY, return the data. Also add an extra check to make // sure it's binary data (seems that it's returned as type STRING) to get around a MySQL // bug (#28214) returning DATE fields with the binary flag set. if ((fieldDefinitions[i].flags & BINARY_FLAG) && (fieldDefinitions[i].type == FIELD_TYPE_STRING)) { cellData = [NSData dataWithBytes:theData length:fieldLengths[i]]; } // For string data, convert to text else { cellData = [NSString stringWithCString:theData encoding:mEncoding]; } break; case FIELD_TYPE_BIT: // Get a binary representation of the data _int2bin(theData[1], fieldDefinitions[i].length, buf); cellData = (theData != NULL) ? [NSString stringWithUTF8String:buf] : @""; free(buf); break; case FIELD_TYPE_TINY_BLOB: case FIELD_TYPE_BLOB: case FIELD_TYPE_MEDIUM_BLOB: case FIELD_TYPE_LONG_BLOB: // For binary data, return the data if force-return-as-string is not enabled if ((fieldDefinitions[i].flags & BINARY_FLAG) && !mReturnDataAsStrings) { cellData = [NSData dataWithBytes:theData length:fieldLengths[i]]; } else { cellData = [[NSString alloc] initWithBytes:theData length:fieldLengths[i] encoding:mEncoding]; if (cellData) [cellData autorelease]; } break; case FIELD_TYPE_NULL: cellData = [NSNull null]; break; default: NSLog(@"in fetchNextRowAsArray : Unknown type : %ld for column %ld, sending back a NSData object", (NSInteger)fieldDefinitions[i].type, (NSInteger)i); cellData = [NSData dataWithBytes:theData length:fieldLengths[i]]; break; } // Free the data if it was originally allocated if (fullyStreaming) free(theData); // If a creator returned a nil object, replace with NSNull if (cellData == nil) cellData = [NSNull null]; } [returnArray insertObject:cellData atIndex:i]; } // If in cached-streaming mode, update the current entry processed count if (!fullyStreaming) { // Lock both mutexes pthread_mutex_lock(&dataCreationLock); pthread_mutex_lock(&dataFreeLock); // Update the active-data pointer to the next item in the list, or set to NULL if no more items currentDataStoreEntry = currentDataStoreEntry->nextRow; // Increment counter processedRowCount++; // Unlock both mutexes pthread_mutex_unlock(&dataCreationLock); pthread_mutex_unlock(&dataFreeLock); } return returnArray; } /* * Ensure the result set is fully processed and freed without any processing * This method ensures that the connection is unlocked. */ - (void) cancelResultLoad { MYSQL_ROW theRow; // Loop through all the rows and ensure the rows are fetched. // If fully streaming, loop through the rows directly if (fullyStreaming) { while (1) { theRow = mysql_fetch_row(mResult); // If no data was returned, we're at the end of the result set - return. if (theRow == NULL) { if (!connectionUnlocked) { [parentConnection unlockConnection]; connectionUnlocked = YES; } return; } } // If in cached-streaming/fast download mode, loop until all data is fetched and freed } else { while (1) { // Check to see whether we need to wait for the data to be available // - if so, wait 1ms before checking again while (!dataDownloaded && processedRowCount == downloadedRowCount) usleep(1000); // If all rows have been processed, we're at the end of the result set - return // once all memory has been freed if (processedRowCount == downloadedRowCount) { while (!dataFreed) usleep(1000); // we don't need to unlock the connection because // the data loading thread already did that return; } processedRowCount++; } } } #pragma mark - #pragma mark Overrides for safety /** * If numOfRows is used before the data is fully downloaded, -1 will be returned; * otherwise the number of rows is returned. */ - (my_ulonglong)numOfRows { if (!dataDownloaded) return -1; return downloadedRowCount; } - (void)dataSeek:(my_ulonglong) row { NSLog(@"dataSeek cannot be used with streaming results"); } @end @implementation MCPStreamingResult (PrivateAPI) /** * Provides a binary representation of the supplied integer (n) in the supplied buffer (buf). The resulting * binary representation will be zero-padded according to the supplied field length (len). */ const char *_int2bin(unsigned int n, unsigned long len, char *buf) { for (int i = (len - 1); i >= 0; --i) { buf[i] = (n & 1) ? '1' : '0'; n >>= 1; } buf[len] = '\0'; } /** * Used internally to download results in a background thread */ - (void)_downloadAllData { NSAutoreleasePool *downloadPool = [[NSAutoreleasePool alloc] init]; MYSQL_ROW theRow; unsigned long *fieldLengths; NSInteger i, dataCopiedLength, rowDataLength; LOCAL_ROW_DATA *newRowStore; size_t sizeOfLocalRowData = sizeof(LOCAL_ROW_DATA); size_t sizeOfDataLengths = (size_t)(sizeof(unsigned long) * mNumOfFields); // Loop through the rows until the end of the data is reached - indicated via a NULL while ( (BOOL)(*isConnectedPtr)(parentConnection, isConnectedSEL) && (theRow = mysql_fetch_row(mResult))) { // Retrieve the lengths of the returned data fieldLengths = mysql_fetch_lengths(mResult); rowDataLength = 0; dataCopiedLength = 0; for (i = 0; i < mNumOfFields; i++) rowDataLength += fieldLengths[i]; // Initialise memory for the row and set a NULL pointer for the next item newRowStore = malloc(sizeOfLocalRowData); newRowStore->nextRow = NULL; // Set up the row data store - a char* - and copy in the data if there is any, // using a null terminator for each field boundary for easier data processing later newRowStore->data = malloc(sizeof(char) * (rowDataLength + mNumOfFields)); for (i = 0; i < mNumOfFields; i++) { if (theRow[i] != NULL) { memcpy(newRowStore->data+dataCopiedLength, theRow[i], fieldLengths[i]); newRowStore->data[dataCopiedLength+fieldLengths[i]] = '\0'; dataCopiedLength += fieldLengths[i] + 1; } else { fieldLengths[i] = NSNotFound; } } // Set up and copy in the field lengths newRowStore->dataLengths = memcpy(malloc(sizeOfDataLengths), fieldLengths, sizeOfDataLengths); // Lock both mutexes pthread_mutex_lock(&dataCreationLock); pthread_mutex_lock(&dataFreeLock); // Add the newly allocated row to end of the storage linked list if (localDataStore) { localDataStoreLastEntry->nextRow = newRowStore; } else { localDataStore = newRowStore; } localDataStoreLastEntry = newRowStore; if (!currentDataStoreEntry) currentDataStoreEntry = newRowStore; // Update the downloaded row count downloadedRowCount++; // Unlock both mutexes pthread_mutex_unlock(&dataCreationLock); pthread_mutex_unlock(&dataFreeLock); } // Unlock the parent connection now data has been retrieved [parentConnection unlockConnection]; connectionUnlocked = YES; dataDownloaded = YES; [downloadPool drain]; } /** * Used internally to free data which has been fully processed; done in a thread to allow * fetchNextRowAsArray to be faster. */ - (void) _freeAllDataWhenDone { NSAutoreleasePool *dataFreeingPool = [[NSAutoreleasePool alloc] init]; while (!dataDownloaded || freedRowCount != downloadedRowCount) { // Lock the data free mutex pthread_mutex_lock(&dataFreeLock); // If the freed row count matches the processed row count, wait before retrying if (freedRowCount == processedRowCount) { pthread_mutex_unlock(&dataFreeLock); usleep(1000); continue; } // Free a single item off the bottom of the list // Update the data pointer to the next item in the list, or set to NULL if no more items LOCAL_ROW_DATA *rowToRemove = localDataStore; localDataStore = localDataStore->nextRow; // Free memory for the first row rowToRemove->nextRow = NULL; free(rowToRemove->dataLengths); if (rowToRemove->data != NULL) free(rowToRemove->data); free(rowToRemove); // Increment the counter freedRowCount++; // Unlock the data free mutex pthread_mutex_unlock(&dataFreeLock); } dataFreed = YES; [dataFreeingPool drain]; } @end