我正在开发一个 iPhone 应用程序，该应用程序涉及将相机中的完整照片（通常在 1.5 到 2.0 MB 之间）以及它们的缩略图（小得多）上传到 Amazon S3。
缩略图总是成功上传，但有时完整的图像不会，当它们失败时，它们会失败，并显示 POSIX 错误代码 12，即 ENOMEM。但是，我添加了调试代码以在发生错误时打印可用内存量，并且总是有相当多的空闲内存，通常超过 100 MB。
此外，当通过 3G 进行上传时，错误出现的频率更高，而通过 wifi 上传时出现的次数更少——这看起来很奇怪，因为请求下载的次数不多，并且正在上传的文件已经在内存中（我也试过从磁盘流式传输，没有任何改进）。
我尝试使用 NSURLConnection、Foundation CFHTTP* 函数和 ASIHTTPRequest 库上传文件，但无论如何，错误以相同的频率发生。更奇怪的是，我的谷歌搜索显示最终用户有时会从 Safari 获得错误代码 12——我还没有看到任何 iOS 开发人员提到它。我正在使用继承的代码库，所以它可能有问题，但我什至不确定要寻找什么。任何见解将不胜感激！
我能够解决此问题的唯一方法是直接使用套接字并手动形成 HTTP 标头。所以我的上传代码目前看起来像这样：
- (void)socketClose
{
[_inputStream setDelegate:nil];
[_inputStream close];
[_inputStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
SCR_RELEASE_SAFELY(_inputStream);
[_outputStream setDelegate:nil];
[_outputStream close];
[_outputStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
SCR_RELEASE_SAFELY(_outputStream);
SCR_RELEASE_SAFELY(_headerBuffer);
}
- (void)sendRequest
{
[self socketClose];
SCR_RELEASE_SAFELY(_headerBuffer);
if (!_shouldCancel)
{
NSString *httpMessage = [NSString stringWithFormat:@"POST upload.php HTTP/1.1\r\n"
"Host:"
#ifndef TESTBED
" %@"
#endif
"\r\n"
"User-Agent: MyApp/3.0.0 CFNetwork/534 Darwin/10.7.0\r\n"
"Content-Length: %d\r\n"
"Accept: */*\r\n"
"Accept-Language: en-us\r\n"
"Accept-Encoding: gzip, deflate\r\n"
"Content-Type: application/x-www-form-urlencoded\r\n"
"Connection: keep-alive\r\n\r\n"
"data="
#ifndef TESTBED
, [self.serverUrl host]
#endif
, _bytesToUpload];
NSString *key = @"data=";
NSData *keyData = [key dataUsingEncoding:NSASCIIStringEncoding];
_bytesToUpload -= [keyData length];
_bytesToUpload = MAX(0, _bytesToUpload);
_headerBuffer = [[NSMutableData alloc] initWithData:[httpMessage dataUsingEncoding:NSUTF8StringEncoding]];
_writtenDataBytes = 0;
CFStreamCreatePairWithSocketToHost(kCFAllocatorDefault
, (CFStringRef)[self.serverUrl host]
#ifdef TESTBED
, 8888
#else
, 80
#endif
, (CFReadStreamRef *)(&_inputStream)
, (CFWriteStreamRef *)(&_outputStream));
[_inputStream setDelegate:self];
[_outputStream setDelegate:self];
[_inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
[_outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
[_inputStream open];
[_outputStream open];
}
}
- (void)stream:(NSStream *)theStream handleEvent:(NSStreamEvent)streamEvent
{
if (_outputStream == theStream)
{
switch (streamEvent)
{
case NSStreamEventOpenCompleted:
{
[self regenerateTimeoutTimer];
break;
}
case NSStreamEventHasSpaceAvailable:
{
SCR_RELEASE_TIMER(_timeoutTimer);
NSInteger length = _headerBuffer.length;
if (length > 0)
{
NSInteger written = [_outputStream write:(const uint8_t *)[_headerBuffer bytes] maxLength:length];
NSInteger rest = length - written;
if (rest > 0)
{
memmove([_headerBuffer mutableBytes], (const uint8_t *)[_headerBuffer mutableBytes] + written, rest);
}
[_headerBuffer setLength:rest];
}
else
{
const uint8_t *dataBytes = [_data bytes];
while ([_outputStream hasSpaceAvailable] && (_writtenDataBytes < _bytesToUpload))
{
NSInteger written = [_outputStream write:dataBytes
maxLength:MIN(_dataLength, _bytesToUpload - _writtenDataBytes)];
if (written > 0)
{
_writtenDataBytes += written;
}
}
}
[self regenerateTimeoutTimer];
break;
}
case NSStreamEventErrorOccurred:
{
SCR_RELEASE_TIMER(_timeoutTimer);
[self reportError:[theStream streamError]];
break;
}
case NSStreamEventEndEncountered:
{
SCR_RELEASE_TIMER(_timeoutTimer);
[self socketClose];
break;
}
}
}
else if (_inputStream == theStream)
{
switch (streamEvent)
{
case NSStreamEventHasBytesAvailable:
{
SCR_RELEASE_TIMER(_timeoutTimer);
/* Read server response here if you wish */
[self socketClose];
break;
}
case NSStreamEventErrorOccurred:
{
SCR_RELEASE_TIMER(_timeoutTimer);
[self reportError:[theStream streamError]];
break;
}
case NSStreamEventEndEncountered:
{
SCR_RELEASE_TIMER(_timeoutTimer);
[self socketClose];
break;
}
}
}
}
尽管 ASIHTTPRequest 可以在这里工作，但我们决定摆脱这种依赖关系，既是为了获得性能，也是为了让一切都在我们自己的控制之下。你可以使用 Wireshark 工具来调试这种东西。
解决此问题的关键是使用流上传文件。使用 NSMutableURLRequest 时，可以使用类似于以下内容的方式来完成：
NSMutableURLRequest* request = [NSMutableURLRequest requestWithURL:url];
[request setHTTPBodyStream:[NSInputStream inputStreamWithFileAtPath:filePath]];
使用 ASIHTTPRequest 时，流式传输文件是通过以下方式完成的：
ASIHTTPRequest* request = [ASIHTTPRequest requestWithURL:url];
[request setPostBodyFilePath:filePath];
rRequest.shouldStreamPostDataFromDisk = YES;
已通过将请求 ( NSMutableUrlConnection) 操作与@autorelease{}主函数一起使用解决了此错误。NSPOXIS 只是偶尔出现。
- (void)main
NSURLConnection* connection;
@autoreleasepool //urgently needed for 3G upload
{
self.currentRequest = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:@"test.php"]];
[self.currentRequest setHTTPMethod:@"PUT"];
[self.currentRequest setHTTPBody:self.data];//inpustStream doesn't work
connection = [NSURLConnection connectionWithRequest:self.currentRequest delegate:self];
[connection start];
}//end autorelease pool
do
{
[[NSRunLoop currentRunLoop] runMode: NSDefaultRunLoopMode beforeDate: [NSDate distantFuture]];
if ([self isCancelled])
{
connection = nil;
isFailed = YES;
break;
}
self.status(statusUpdateMessage);
}
while (!isFailed && !isCompleted);
[timer invalidate];//test
timer = nil;
//corresponding of status via blocks
self.completed(!isFailed);
self.status(isFailed ? errorMessage : @"Completed");
if (isFailed)
{
self.failed(errorMessage != nil ? errorMessage : @"Undefined error");
}
self.data = nil;
self.currentRequest = nil;
connection = nil;
}