Add IOS readStream event frequency limitation

Author: wkh237

src/ios/RNFetchBlob/RNFetchBlob.m

@@ -15,6 +15,8 @@
 
 
 RCTBridge * bridgeRef;
+dispatch_queue_t commonTaskQueue;
+dispatch_queue_t fsQueue;
 
 ////////////////////////////////////////
 //
@@ -30,7 +32,9 @@ @implementation RNFetchBlob
 @synthesize bridge = _bridge;
 
 - (dispatch_queue_t) methodQueue {
-    return dispatch_queue_create("RNFetchBlob.queue", DISPATCH_QUEUE_SERIAL);
+    if(commonTaskQueue == nil)
+        commonTaskQueue = dispatch_queue_create("RNFetchBlob.queue", DISPATCH_QUEUE_SERIAL);
+    return commonTaskQueue;
 }
 
 + (RCTBridge *)getRCTBridge
@@ -43,6 +47,10 @@ + (RCTBridge *)getRCTBridge
 - (id) init {
     self = [super init];
     self.filePathPrefix = FILE_PREFIX;
+    if(commonTaskQueue == nil)
+        commonTaskQueue = dispatch_queue_create("RNFetchBlob.queue", DISPATCH_QUEUE_SERIAL);
+    if(fsQueue == nil)
+        fsQueue = dispatch_queue_create("RNFetchBlob.fs.queue", DISPATCH_QUEUE_SERIAL);
     BOOL isDir;
     // if temp folder not exists, create one
     if(![[NSFileManager defaultManager] fileExistsAtPath: [RNFetchBlobFS getTempPath] isDirectory:&isDir]) {
@@ -376,17 +384,16 @@ - (NSDictionary *)constantsToExport
 #pragma mark - fs.readStream
 RCT_EXPORT_METHOD(readStream:(NSString *)path withEncoding:(NSString *)encoding bufferSize:(int)bufferSize tick:(int)tick streamId:(NSString *)streamId
 {
-
-//    RNFetchBlobFS *fileStream = [[RNFetchBlobFS alloc] initWithBridgeRef:self.bridge];
     if(bufferSize == nil) {
         if([[encoding lowercaseString] isEqualToString:@"base64"])
             bufferSize = 4095;
         else
             bufferSize = 4096;
     }
 
-//    [fileStream readWithPath:path useEncoding:encoding bufferSize:bufferSize];
-    [RNFetchBlobFS readStream:path encoding:encoding bufferSize:bufferSize tick:tick streamId:streamId bridgeRef:_bridge];
+    dispatch_async(fsQueue, ^{
+        [RNFetchBlobFS readStream:path encoding:encoding bufferSize:bufferSize tick:tick streamId:streamId bridgeRef:_bridge];
+    });
 })
 
 #pragma mark - fs.getEnvionmentDirs

src/ios/RNFetchBlobFS.m

@@ -128,9 +128,10 @@ + (void) readStream:(NSString *)uri
 {
     [[self class] getPathFromUri:uri completionHandler:^(NSString *path, ALAssetRepresentation *asset) {
 
-        RCTEventDispatcher * event = bridgeRef.eventDispatcher;
-        int read = 0;
-        int chunkSize = bufferSize;
+        __block RCTEventDispatcher * event = bridgeRef.eventDispatcher;
+        __block int read = 0;
+        __block int backoff = tick *1000;
+        __block int chunkSize = bufferSize;
         // allocate buffer in heap instead of stack
         uint8_t * buffer;
         @try
@@ -151,6 +152,10 @@ + (void) readStream:(NSString *)uri
                 while((read = [stream read:buffer maxLength:bufferSize]) > 0)
                 {
                     [[self class] emitDataChunks:[NSData dataWithBytes:buffer length:read] encoding:encoding streamId:streamId event:event];
+                    if(tick > 0)
+                    {
+                        usleep(backoff);
+                    }
                 }
                 [stream close];
             }
@@ -162,6 +167,10 @@ + (void) readStream:(NSString *)uri
                 {
                     cursor += read;
                     [[self class] emitDataChunks:[NSData dataWithBytes:buffer length:read] encoding:encoding streamId:streamId event:event];
+                    if(tick > 0)
+                    {
+                        usleep(backoff);
+                    }
                 }
             }
             else