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Use JSStringCreateWithUTF8CString and skip NSString decoding when loading the bundle

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Summary: public

Benchmarking our startup path has shown we spend a lot of time decoding strings (iPhone 4S / iPhone 5):

* reading a 2MB JS bundle: 35ms / 15ms
* decoding is to an `NSString`: 186ms / 78ms
* transforming that to a `JSString`: 29ms / 10ms

Instead of going through an `NSString` transformation, we generate a null-terminated bundle (0.1ms / 0.05ms to copy the data) and use `JSStringCreateWithUTF8CString` (121ms / 53ms) to generate the string. That makes decoding 70% faster.

Reviewed By: javache

Differential Revision: D2541140

fb-gh-sync-id: 09a016b8edfd46a9b62682c76705564d2024e75e
This commit is contained in:
Frédéric Sagnes
2015-10-16 08:10:25 -07:00
committed by facebook-github-bot-3
parent 8e2ec64763
commit 4a3857ef1d
10 changed files with 47 additions and 35 deletions
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10
React/Base/RCTJavaScriptLoader.m
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@@ -36,8 +36,10 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
NSString *filePath = scriptURL.path;
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
NSError *error = nil;
NSString *rawText = [NSString stringWithContentsOfFile:filePath usedEncoding:NULL error:&error];
onComplete(error, rawText);
NSData *source = [NSData dataWithContentsOfFile:filePath
options:NSDataReadingMappedIfSafe
error:&error];
onComplete(error, source);
});
return;
}
@@ -71,10 +73,10 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
encoding = CFStringConvertEncodingToNSStringEncoding(cfEncoding);
}
}
NSString *rawText = [[NSString alloc] initWithData:data encoding:encoding];
// Handle HTTP errors
if ([response isKindOfClass:[NSHTTPURLResponse class]] && ((NSHTTPURLResponse *)response).statusCode != 200) {
NSString *rawText = [[NSString alloc] initWithData:data encoding:encoding];
NSDictionary *userInfo;
NSDictionary *errorDetails = RCTJSONParse(rawText, nil);
if ([errorDetails isKindOfClass:[NSDictionary class]] &&
@@ -101,7 +103,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
onComplete(error, nil);
return;
}
onComplete(nil, rawText);
onComplete(nil, data);
}];
[task resume];