在iOS上使用RNCryptor加密/解密大文件时出现内存问题 [英] Memory issues when encrypting/decrypting a large file with RNCryptor on iOS
问题描述
我正在尝试使用RNCryptor加密和解密iOS上的大文件（600 + MB）。在 github 上，我找到了示例代码如何在流上异步使用库。此代码类似于Rob Napier关于关于同一主题的问题的答案。
I'm trying to use RNCryptor to encrypt and decrypt large files (600+MB) on iOS. On the github I found example code on how to use the library asynchronously on streams. This code is similar to the answer of Rob Napier on a question about this same subject.
然而，虽然我认为我正确实现了代码，但该应用程序使用高达1.5 GB的内存（在iPad 6.1模拟器中）。我认为代码应该阻止应用程序在内存中保留多个数据块？出了什么问题？
However, although I think I implemented the code correctly, the app uses up to 1.5 GB of memory (in the iPad 6.1 simulator). I thought the code was supposed to prevent the app from keeping more than one block of data in-memory? So what is going wrong?
在我的控制器中，我创建了一个'CryptController'，我用加密/解密请求发送消息。
In my controller, I create a 'CryptController' which I message with encrypt/decrypt requests.
// Controller.m
NSString *password = @"pw123";
self.cryptor = [[CryptController alloc] initWithPassword:password];
//start encrypting file
[self.cryptor streamEncryptRequest:self.fileName andExtension:@"pdf" withURL:[self samplesURL]];
//wait for encryption to finish
NSDate *timeout = [NSDate dateWithTimeIntervalSinceNow:1];
do {
[[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode
beforeDate:timeout];
} while (![self.cryptor isFinished]);
在CryptController中我有：
In CryptController I have:
- (void)streamEncryptionDidFinish {
if (self.cryptor.error) {
NSLog(@"An error occurred. You cannot trust decryptedData at this point");
}
else {
NSLog(@"%@ is complete. Use it as you like", [self.tempURL lastPathComponent]);
}
self.cryptor = nil;
self.isFinished = YES;
}
- (void) streamEncryptRequest:(NSString *)fileName andExtension:(NSString *)ext withURL:(NSURL *)directory {
//Make sure that this number is larger than the header + 1 block.
int blockSize = 32 * 1024;
NSString *encryptedFileName = [NSString stringWithFormat:@"streamEnc_%@", fileName];
self.tempURL = [[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory inDomain:NSUserDomainMask appropriateForURL:nil create:NO error:nil];
self.tempURL = [self.tempURL URLByAppendingPathComponent:encryptedFileName isDirectory:NO];
self.tempURL = [self.tempURL URLByAppendingPathExtension:@"crypt"];
NSInputStream *decryptedStream = [NSInputStream inputStreamWithURL:[[directory URLByAppendingPathComponent:fileName isDirectory:NO] URLByAppendingPathExtension:ext]];
NSOutputStream *cryptedStream = [NSOutputStream outputStreamWithURL:self.tempURL append:NO];
[cryptedStream open];
[decryptedStream open];
__block NSMutableData *data = [NSMutableData dataWithLength:blockSize];
__block RNEncryptor *encryptor = nil;
dispatch_block_t readStreamBlock = ^{
[data setLength:blockSize];
NSInteger bytesRead = [decryptedStream read:[data mutableBytes] maxLength:blockSize];
if (bytesRead < 0) {
//Throw an error
}
else if (bytesRead == 0) {
[encryptor finish];
}
else {
[data setLength:bytesRead];
[encryptor addData:data];
//NSLog(@"Sent %ld bytes to encryptor", (unsigned long)bytesRead);
}
};
encryptor = [[RNEncryptor alloc] initWithSettings:kRNCryptorAES256Settings
password:self.password
handler:^(RNCryptor *cryptor, NSData *data) {
//NSLog(@"Encryptor received %ld bytes", (unsigned long)data.length);
[cryptedStream write:data.bytes maxLength:data.length];
if (cryptor.isFinished) {
[decryptedStream close];
//call my delegate that i'm finished with decrypting
[self streamEncryptionDidFinish];
}
else {
readStreamBlock();
}
}];
// Read the first block to kick things off
self.isFinished = NO;
readStreamBlock();
}
当我使用分配工具进行分析时，我看到的分配类别一直在增长 malloc 32.50 KB ， malloc 4.00 KB ， NSConcreteData 和 NSSubrangeData 。特别是 malloc 32.50 KB 增长很大，超过1 GB。负责的调用者是
[NSConcreteData initWithBytes：length：copy：freeWhenDone：bytesAreVM：]
对于 NSConcreteData 负责的来电者是
- [NSData（NSData）copyWithZone：] 。
When I profile using the Allocation Instrument, the allocation categories I see consistently growing are malloc 32.50 KB, malloc 4.00 KB, NSConcreteData and NSSubrangeData. Especially the malloc 32.50 KB grows big, over 1 GB. The responsible caller is
[NSConcreteData initWithBytes:length:copy:freeWhenDone:bytesAreVM:]
For NSConcreteData the responsible caller is
-[NSData(NSData) copyWithZone:].
当我使用泄漏仪器进行了剖析，没有发现泄漏。
When I profile using the Leaks Instrument, no leaks are found.
我是Objective-C的新手，根据我的理解，新的ARC应该处理分配和释放内存。在搜索与内存相关的任何内容时，我发现的所有信息都假设您不使用ARC（或者在编写时它不存在）。我确定使用ARC，因为当我尝试手动释放内存时，我收到编译错误。
I'm new to Objective-C, and from what I understood, the new ARC is supposed to handle allocation and deallocation of memory. When googling on anything memory related, all the information I find is assuming you don't use ARC (or it didn't exist at time of writing). I sure am using ARC, since I get compile errors saying so when I try to manually deallocate memory.
如果有人能帮助我，我们将不胜感激！如果需要更多信息，我很乐意提供它:)
另外，我是StackOverflow的新手，所以如果有什么我忽略了我应该做的事情，请通知我！
If anyone can help me with this, it would be greatly appreciated! If any more information is needed, I'll be happy to provide it :) Also, I'm new to StackOverflow, so if there's anything I've overlooked that I should have done, kindly inform me!
推荐答案
我终于尝试了这里给出的解决方案，它使用信号量而不是依赖回调来等待流。这完美地运行:)根据Allocations Instrument，内存使用率徘徊在1.1 MB左右。由于信号量语法，它看起来可能不那么整洁，但至少它做了我需要做的事情。
I finally tried the solution given here, which uses semaphores instead of depending on the callback to wait for the stream. This works perfectly :) The memory usage hovers around 1.1 MB according to the Allocations Instrument. It may not look as neat because of the semaphore syntax, but at least it does what I need it to do.
当然，欢迎其他建议：）
Other suggestions are still welcome of course :)
- (void)encryptWithSemaphore:(NSURL *)url {
dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
__block int total = 0;
int blockSize = 32 * 1024;
NSString *encryptedFile = [[url lastPathComponent] stringByDeletingPathExtension];
NSURL *docsURL = [[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory inDomain:NSUserDomainMask appropriateForURL:nil create:NO error:nil];
self.tempURL = [[docsURL URLByAppendingPathComponent:encryptedFile isDirectory:NO] URLByAppendingPathExtension:@"crypt"];
NSInputStream *inputStream = [NSInputStream inputStreamWithURL:url];
__block NSOutputStream *outputStream = [NSOutputStream outputStreamWithURL:self.tempURL append:NO];
__block NSError *encryptionError = nil;
[inputStream open];
[outputStream open];
RNEncryptor *encryptor = [[RNEncryptor alloc] initWithSettings:kRNCryptorAES256Settings
password:self.password
handler:^(RNCryptor *cryptor, NSData *data) {
@autoreleasepool {
[outputStream write:data.bytes maxLength:data.length];
dispatch_semaphore_signal(semaphore);
data = nil;
if (cryptor.isFinished) {
[outputStream close];
encryptionError = cryptor.error;
// call my delegate that I'm finished with decrypting
}
}
}];
while (inputStream.hasBytesAvailable) {
@autoreleasepool {
uint8_t buf[blockSize];
NSUInteger bytesRead = [inputStream read:buf maxLength:blockSize];
if (bytesRead > 0) {
NSData *data = [NSData dataWithBytes:buf length:bytesRead];
total = total + bytesRead;
[encryptor addData:data];
dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
}
}
}
[inputStream close];
[encryptor finish];
}
这篇关于在iOS上使用RNCryptor加密/解密大文件时出现内存问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
