- Change MCPStreamingResult to use a safer streaming mode by default - download all results as fast as possible from the server, to avoid blocking, but do so in a background thread to allow results processing to start as soon as data is available. Many thanks to Hans-Jörg Bibiko for assistance with this.

 - Add an option to the SQL export dialog to allow selection of the full-streaming method, with a warning that it may block table UPDATES/INSERTS.

1 files changed, 314 insertions, 120 deletions

diff --git a/Frameworks/MCPKit/MCPFoundationKit/MCPStreamingResult.m b/Frameworks/MCPKit/MCPFoundationKit/MCPStreamingResult.m
index 5eb147d3..63353056 100644
--- a/Frameworks/MCPKit/MCPFoundationKit/MCPStreamingResult.m
+++ b/Frameworks/MCPKit/MCPFoundationKit/MCPStreamingResult.m
@@ -1,5 +1,5 @@
 //
-//	$Id$
+//  $Id$
 //
 //  MCPStreamingResult.m
 //  sequel-pro
@@ -31,11 +31,24 @@
 /**
  * IMPORTANT NOTE
  *
- * MCPStreamingResult can produce fast and low-memory result reads, but should not
- * be widely used for reads as it can result in MySQL thread or table blocking.
+ * 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)
+- (void) _downloadAllData;
+- (void) _freeAllDataWhenDone;
+@end
+
 @implementation MCPStreamingResult : MCPResult
 
 #pragma mark -
@@ -47,36 +60,64 @@
  */
 - (id)initWithMySQLPtr:(MYSQL *)mySQLPtr encoding:(NSStringEncoding)theEncoding timeZone:(NSTimeZone *)theTimeZone connection:(MCPConnection *)theConnection
 {
-	if ((self = [super init])) {
-		mEncoding = theEncoding;
-		mTimeZone = [theTimeZone retain];
-		parentConnection = theConnection;
-		
-		if (mResult) {
-			mysql_free_result(mResult);
-			mResult = NULL;
-		}
-		
-		if (mNames) {
-			[mNames release];
-			mNames = NULL;
-		}
-		
-		mResult = mysql_use_result(mySQLPtr);
-		
-		if (mResult) {
-			mNumOfFields = mysql_num_fields(mResult);
-			fieldDefinitions = mysql_fetch_fields(mResult);
-		} else {
-			mNumOfFields = 0;
-		}
-		
-		if (mMySQLLocales == NULL) {
-			mMySQLLocales = [[MCPConnection getMySQLLocales] retain];
-		}
-	}
-	
-	return self;
+    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;
+        
+        if (mResult) {
+            mysql_free_result(mResult);
+            mResult = NULL;
+        }
+        
+        if (mNames) {
+            [mNames release];
+            mNames = NULL;
+        }
+        
+        mResult = mysql_use_result(mySQLPtr);
+        
+        if (mResult) {
+            mNumOfFields = mysql_num_fields(mResult);
+            fieldDefinitions = mysql_fetch_fields(mResult);
+        } else {
+            mNumOfFields = 0;
+        }
+
+		// 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;
+
+            // 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;
 }
 
 /**
@@ -84,9 +125,9 @@
  */
 - (void) dealloc
 {
-	[parentConnection unlockConnection];
-	
-	[super dealloc];
+    [parentConnection unlockConnection];
+    
+    [super dealloc];
 }
 
 #pragma mark -
@@ -98,100 +139,149 @@
  */
 - (NSArray *)fetchNextRowAsArray
 {
-	MYSQL_ROW theRow;
-	unsigned long *fieldLengths;
-	int i;
-	NSMutableArray *returnArray;
+    MYSQL_ROW theRow;
+	char *theRowData;
+    unsigned long *fieldLengths;
+    int i, copiedDataLength;
+    NSMutableArray *returnArray;
 
-	// Retrieve the next row
-	theRow = mysql_fetch_row(mResult);
+    // 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 - return nil.
-	if (theRow == NULL) return nil;
+        // If no data was returned, we're at the end of the result set - return nil.
+        if (theRow == NULL) return nil;
 
-	// Retrieve the lengths of the returned data
-	fieldLengths = mysql_fetch_lengths(mResult);
+        // Retrieve the lengths of the returned data
+        fieldLengths = mysql_fetch_lengths(mResult);
 
-	// Initialise the array to return
-	returnArray = [NSMutableArray arrayWithCapacity:mNumOfFields];
-	for (i = 0; i < mNumOfFields; i++) {
-		id cellData;
+	// If in cached-streaming/fast download mode, get a reference to the data for the current row
+    } else {
+		copiedDataLength = 0;
+        
+        // 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) {
+            usleep(1000);
+        }
 
-		// Use NSNulls for the NULL data type
-		if (theRow[i] == NULL) {
-			cellData = [NSNull null];
+        // 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) {
+			while (!dataFreed) usleep(1000);
+			return nil;
+		}
 
-		// Otherwise, switch by data type
-		} else {
+        // Retrieve a reference to the data and the associated lengths
+        theRowData = currentDataStoreEntry->data;
+        fieldLengths = currentDataStoreEntry->dataLengths;
+    }
 
-			// Create a null-terminated data string for processing
-			char *theData = calloc(sizeof(char), fieldLengths[i]+1);
-			memcpy(theData, theRow[i], fieldLengths[i]);
-			theData[fieldLengths[i]] = '\0';
-
-			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...
-					cellData = [NSString stringWithCString:theData encoding:mEncoding];
-					break;
-					
-				case FIELD_TYPE_BIT:
-					cellData = [NSString stringWithFormat:@"%u", theData[0]];
-					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 (fieldDefinitions[i].flags & BINARY_FLAG) {
-						cellData = [NSData dataWithBytes:theData length:fieldLengths[i]];
-
-					// For string data, convert to text
-					} 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 : %d for column %d, sending back a NSData object", (int)fieldDefinitions[i].type, (int)i);
-					cellData = [NSData dataWithBytes:theData length:fieldLengths[i]];
-					break;
+    // Initialise the array to return
+    returnArray = [NSMutableArray arrayWithCapacity:mNumOfFields];
+    for (i = 0; i < mNumOfFields; i++) {
+        id cellData = nil;
+		char *theData;
+
+		// 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;
+			}
+		}
 
-			free(theData);
+        // 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) {
 
-			// If a creator returned a nil object, replace with NSNull
-			if (cellData == nil) cellData = [NSNull null];
-		}
+            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...
+                    cellData = [NSString stringWithCString:theData encoding:mEncoding];
+                    break;
+                    
+                case FIELD_TYPE_BIT:
+                    cellData = [NSString stringWithFormat:@"%u", theData[0]];
+                    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 (fieldDefinitions[i].flags & BINARY_FLAG) {
+                        cellData = [NSData dataWithBytes:theData length:fieldLengths[i]];
+
+                    // For string data, convert to text
+                    } 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 : %d for column %d, sending back a NSData object", (int)fieldDefinitions[i].type, (int)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];
+    }
 
-		[returnArray insertObject:cellData atIndex:i];
+	// If in cached-streaming mode, update the current entry processed count
+	if (!fullyStreaming) {
+
+        // 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++;
 	}
 
-	return returnArray;
+    return returnArray;
 }
 
 #pragma mark -
@@ -199,13 +289,117 @@
 
 - (my_ulonglong) numOfRows
 {
-	NSLog(@"numOfRows cannot be used with streaming results");
-	return 0;
+    NSLog(@"numOfRows cannot be used with streaming results");
+    return 0;
 }
 
 - (void) dataSeek:(my_ulonglong) row
 {
-	NSLog(@"dataSeek cannot be used with streaming results");
+    NSLog(@"dataSeek cannot be used with streaming results");
+}
+
+@end
+
+@implementation MCPStreamingResult (PrivateAPI)
+
+/**
+ * Used internally to download results in a background thread
+ */
+- (void) _downloadAllData
+{
+	NSAutoreleasePool *downloadPool = [[NSAutoreleasePool alloc] init];
+    MYSQL_ROW theRow;
+    unsigned long *fieldLengths;
+    int 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 (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
+		if (rowDataLength) {
+			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;
+				}
+			}
+		} else {
+			newRowStore->data = NULL;
+		}
+		
+		// Set up and copy in the field lengths
+		newRowStore->dataLengths = memcpy(malloc(sizeOfDataLengths), fieldLengths, sizeOfDataLengths);
+
+		// 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++;
+    }
+
+    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) {
+	
+		// If the freed row count matches the processed row count, wait before retrying
+		if (freedRowCount == processedRowCount) {
+			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++;
+	}
+	
+	dataFreed = YES;
+	[dataFreeingPool drain];
 }
 
 @end
\ No newline at end of file