Add tests for upload / download throttling

Cleanup API
More comments as I'll never remember what all this stuff was for

@@ -462,8 +462,17 @@ extern unsigned long const ASIWWANBandwidthThrottleAmount;
 + (unsigned long)maxBandwidthPerSecond;
 + (void)setMaxBandwidthPerSecond:(unsigned long)bytes;
 
+// Get a rough average (for the last 5 seconds) of how much bandwidth is being used, in bytes
 + (unsigned long)averageBandwidthUsedPerSecond;
 
+// Will return YES is bandwidth throttling is currently in use
++ (BOOL)isBandwidthThrottled;
+
+// Used internally to record bandwidth use, and by ASIInputStreams when uploading. It's probably best if you don't mess with this.
++ (void)incrementBandwidthUsedInLastSecond:(unsigned long)bytes;
+
+// On iPhone only, ASIHTTPRequest can automatically turn throttling on and off as the connection type changes between WWAN and WiFi
+
 #if TARGET_OS_IPHONE
 // Set to YES to automatically turn on throttling when WWAN is connected, and automatically turn it off when it isn't
 + (void)setShouldThrottleBandwidthForWWAN:(BOOL)throttle;

@@ -72,16 +72,14 @@ unsigned long const ASIWWANBandwidthThrottleAmount = 14800;
 // YES when bandwidth throttling is active
 // This flag does not denote whether throttling is turned on - rather whether it is currently in use
 // It will be set to NO when throttling is turned on, but a WI-FI connection is active
-BOOL shouldThrottleBandwidth = NO;
+BOOL isBandwidthThrottled = NO;
 
 // Private stuff
 @interface ASIHTTPRequest ()
 
 - (BOOL)askDelegateForCredentials;
 - (BOOL)askDelegateForProxyCredentials;
-+ (void)incrementBandwidthUsedInLastSecond:(unsigned long)bytes;
 + (void)measureBandwidthUsage;
-+ (BOOL)shouldThrottleBandwidth;
 + (void)recordBandwidthUsage;
 
 @property (assign) BOOL complete;
@@ -1660,7 +1658,7 @@ BOOL shouldThrottleBandwidth = NO;
 	// Reduce the buffer size if we're receiving data too quickly when bandwidth throttling is active
 	// This just augments the throttling done in measureBandwidthUsage to reduce the amount we go over the limit
 	
-	if ([[self class] shouldThrottleBandwidth]) {
+	if ([[self class] isBandwidthThrottled]) {
 		[bandwidthThrottlingLock lock];
 		if (maxBandwidthPerSecond > 0) {
 			long long maxSize  = (long long)maxBandwidthPerSecond-(long long)bandwidthUsedInLastSecond;
@@ -2319,11 +2317,11 @@ BOOL shouldThrottleBandwidth = NO;
 
 #pragma mark bandwidth measurement / throttling
 
-+ (BOOL)shouldThrottleBandwidth
++ (BOOL)isBandwidthThrottled
 {
 #if TARGET_OS_IPHONE
 	[bandwidthThrottlingLock lock];
-	BOOL throttle = shouldThrottleBandwidth;
+	BOOL throttle = isBandwidthThrottled;
 	[bandwidthThrottlingLock unlock];
 	return throttle;
 #else
@@ -2419,7 +2417,7 @@ BOOL shouldThrottleBandwidth = NO;
 }
 
 #if TARGET_OS_IPHONE
-+ (void)setShouldThrottleBandwidthForWWAN:(BOOL)throttle
++ (void)setisBandwidthThrottledForWWAN:(BOOL)throttle
 {
 	if (throttle) {
 		[ASIHTTPRequest throttleBandwidthForWWANUsingLimit:ASIWWANBandwidthThrottleAmount];
@@ -2443,9 +2441,9 @@ BOOL shouldThrottleBandwidth = NO;
 {
 	[bandwidthThrottlingLock lock];	
 	if ([[Reachability sharedReachability] internetConnectionStatus] == ReachableViaCarrierDataNetwork) {
-		shouldThrottleBandwidth = YES;
+		isBandwidthThrottled = YES;
 	} else {
-		shouldThrottleBandwidth = NO;
+		isBandwidthThrottled = NO;
 	}
 	[bandwidthThrottlingLock unlock];
 }
@@ -2455,15 +2453,18 @@ BOOL shouldThrottleBandwidth = NO;
 {
 
 	[bandwidthThrottlingLock lock];
-	unsigned long toRead = 4096;
-	if (maxBandwidthPerSecond) {
-		toRead = maxBandwidthPerSecond/32;
-	}
+	
+	// We'll split our bandwidth allowance into 4 (which is the default for an ASINetworkQueue's max concurrent operations count) to give all running requests a fighting chance of reading data this cycle
+	long long toRead = maxBandwidthPerSecond/4;
 	if (maxBandwidthPerSecond > 0 && (bandwidthUsedInLastSecond + toRead > maxBandwidthPerSecond)) {
+		toRead = maxBandwidthPerSecond-bandwidthUsedInLastSecond;
+		if (toRead < 0) {
 			toRead = 0;
 		}
+	}
 
 	if (toRead == 0 || !bandwidthMeasurementDate || [bandwidthMeasurementDate timeIntervalSinceNow] < -0) {
+		NSLog(@"sleep");
 		[NSThread sleepUntilDate:bandwidthMeasurementDate];
 		[self recordBandwidthUsage];
 	}

@@ -31,32 +31,48 @@
 	[super dealloc];
 }
 
+
+// Ok, so this works, but I don't really understand why.
+// Ideally, we'd just return the stream's hasBytesAvailable, but CFNetwork seems to want to monopolise our run loop until (presumably) its buffer is full, which will cause timeouts if we're throttling the bandwidth
+// We return NO when we shouldn't be uploading any more data because our bandwidth limit has run out (for now)
+// The call to maxUploadReadLength will recognise that we've run out of our allotted bandwidth limit, and sleep this thread for the rest of the measurement period
+// This method will be called again, but we'll almost certainly return YES the next time around, because we'll have more limit to use up
+// The NO returns seem to snap CFNetwork out of its reverie, and return control to the main loop in loadRequest, so that we can manage timeouts and progress delegate updates
 - (BOOL)hasBytesAvailable
 {
+	if ([ASIHTTPRequest isBandwidthThrottled]) {
 		if ([ASIHTTPRequest maxUploadReadLength] == 0) {
-		NSLog(@"no");
 			return NO;
 		}
-	NSLog(@"yes");
+	}
 	return [[self stream] hasBytesAvailable];
 	
 }
 
+// Called when CFNetwork wants to read more of our request body
+// When throttling is on, we ask ASIHTTPRequest for the maximum amount of data we can read
 - (NSInteger)read:(uint8_t *)buffer maxLength:(NSUInteger)len
 {
-	unsigned long toRead = [ASIHTTPRequest maxUploadReadLength];
-	//NSLog(@"may read %lu",toRead);
+	unsigned long toRead = len;
+	if ([ASIHTTPRequest isBandwidthThrottled]) {
+		toRead = [ASIHTTPRequest maxUploadReadLength];
 		if (toRead > len) {
 			toRead = len;
+		
+		// Hopefully this won't happen because hasBytesAvailable will have returned NO, but just in case - we need to read at least 1 byte, or bad things might happen
 		} else if (toRead == 0) {
 			toRead = 1;
 		}
-	//toRead = len;
+		NSLog(@"Throttled read %u",toRead);
+	} else {
+		NSLog(@"Unthrottled read %u",toRead);
+	}
 	[ASIHTTPRequest incrementBandwidthUsedInLastSecond:toRead];
-	//NSLog(@"will read %lu",toRead);
 	return [[self stream] read:buffer maxLength:toRead];
 }
 
+// If we get asked to perform a method we don't have (which is almost all of them), we'll just forward the message to our stream
+
 - (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector
 {
 	return [[self stream] methodSignatureForSelector:aSelector];

@@ -37,4 +37,6 @@
 - (void)testCompression;
 - (void)testSubclass;
 - (void)testTimeOutWithoutDownloadDelegate;
+- (void)testThrottlingDownloadBandwidth;
+- (void)testThrottlingUploadBandwidth;
 @end

@@ -794,6 +794,68 @@
 }
 
 
+- (void)testThrottlingDownloadBandwidth
+{
+	[ASIHTTPRequest setMaxBandwidthPerSecond:0];
+	
+	// This content is around 128KB in size, and it won't be gzipped, so it should take more than 8 seconds to download at 14.5KB / second
+	// We'll test first without throttling
+	ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:[NSURL URLWithString:@"http://asi/ASIHTTPRequest/tests/the_great_american_novel_%28abridged%29.txt"]];
+	NSDate *date = [NSDate date];
+	[request start];	
+	
+	NSTimeInterval interval =[date timeIntervalSinceNow];
+	BOOL success = (interval > -7);
+	GHAssertTrue(success,@"Downloaded the file too slowly - either this is a bug, or your internet connection is too slow to run this test (must be able to download 128KB in less than 7 seconds, without throttling)");
+	
+	// Now we'll test with throttling
+	[ASIHTTPRequest setMaxBandwidthPerSecond:ASIWWANBandwidthThrottleAmount];
+	request = [ASIHTTPRequest requestWithURL:[NSURL URLWithString:@"http://asi/ASIHTTPRequest/tests/the_great_american_novel_%28abridged%29.txt"]];
+	date = [NSDate date];
+	[request start];	
+	
+	[ASIHTTPRequest setMaxBandwidthPerSecond:0];
+	
+	interval =[date timeIntervalSinceNow];
+	success = (interval < -7);
+	GHAssertTrue(success,@"Failed to throttle download");		
+	GHAssertNil([request error],@"Request generated an error - timeout?");	
+	
+}
+
+- (void)testThrottlingUploadBandwidth
+{
+	[ASIHTTPRequest setMaxBandwidthPerSecond:0];
+	
+	// Create a 64KB request body
+	NSData *data = [[[NSMutableData alloc] initWithLength:64*1024] autorelease];
+	
+	// We'll test first without throttling
+	ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:[NSURL URLWithString:@"http://asi/ignore"]];
+	[request appendPostData:data];
+	NSDate *date = [NSDate date];
+	[request start];	
+	
+	NSTimeInterval interval =[date timeIntervalSinceNow];
+	BOOL success = (interval > -3);
+	GHAssertTrue(success,@"Uploaded the data too slowly - either this is a bug, or your internet connection is too slow to run this test (must be able to upload 64KB in less than 3 seconds, without throttling)");
+	
+	// Now we'll test with throttling
+	[ASIHTTPRequest setMaxBandwidthPerSecond:ASIWWANBandwidthThrottleAmount];
+	request = [ASIHTTPRequest requestWithURL:[NSURL URLWithString:@"http://asi/ignore"]];
+	[request appendPostData:data];
+	date = [NSDate date];
+	[request start];	
+	
+	[ASIHTTPRequest setMaxBandwidthPerSecond:0];
+	
+	interval =[date timeIntervalSinceNow];
+	success = (interval < -3);
+	GHAssertTrue(success,@"Failed to throttle upload");		
+	GHAssertNil([request error],@"Request generated an error - timeout?");	
+	
+}
+
 @end