Bartosz Dziewoński has uploaded a new change for review.
https://gerrit.wikimedia.org/r/297347
Change subject: mw.FormDataTransport: Work around call stack limits for chunked
uploads
......................................................................
mw.FormDataTransport: Work around call stack limits for chunked uploads
In jQuery 2.x, nested promises result in nested call stacks when
resolving/rejecting/notifying the last promise in the chain and
listening on the first one, and browsers have call stack limits low
enough that we previously ran into them for files around a couple
hundred megabytes (the worst is Firefox 47 with a limit of 1024
calls).
Write some custom logic without chaining (just manual calls to
done/fail/progress and resolve/reject/notify), so that we never have
to go through 800 function calls when finishing the upload and
resolving a promise.
Bug: T130610
Change-Id: Ia34134f4aac58d80a2752efe8103fdf3646e6078
---
M resources/transports/mw.FormDataTransport.js
1 file changed, 51 insertions(+), 16 deletions(-)
git pull ssh://gerrit.wikimedia.org:29418/mediawiki/extensions/UploadWizard
refs/changes/47/297347/1
diff --git a/resources/transports/mw.FormDataTransport.js
b/resources/transports/mw.FormDataTransport.js
index d97fb12..e637d17 100644
--- a/resources/transports/mw.FormDataTransport.js
+++ b/resources/transports/mw.FormDataTransport.js
@@ -107,8 +107,7 @@
* @return {jQuery.Promise}
*/
mw.FormDataTransport.prototype.upload = function ( file ) {
- var formData, deferred, ext, totalUploaded,
- chunkSize = this.chunkSize,
+ var formData, deferred, ext,
transport = this;
// use timestamp + filename to avoid conflicts on server
@@ -123,18 +122,8 @@
this.tempname = this.tempname.substr( 0, 240 -
ext.length - 1 ) + '.' + ext;
}
- if ( file.size > chunkSize ) {
- totalUploaded = 0;
- // The progress notifications give us per-chunk
progress, filter them to get progress
- // for the whole file
- return this.uploadChunk( file, 0 ).then( null, null,
function ( fraction ) {
- if ( fraction === 1 ) {
- // We completed a chunk
- totalUploaded += chunkSize;
- fraction = 0;
- }
- return ( totalUploaded + fraction * chunkSize )
/ file.size;
- } );
+ if ( file.size > this.chunkSize ) {
+ return this.chunkedUpload( file );
} else {
deferred = $.Deferred();
this.xhr = this.createXHR( deferred );
@@ -155,6 +144,53 @@
return deferred.promise();
}
+ };
+
+ /**
+ * This function exists to safely chain several hundred promises
without using .then() or nested
+ * promises. We might divide a 4 GB file into 800 chunks of 5 MB each.
+ *
+ * In jQuery 2.x, nested promises result in nested call stacks when
resolving/rejecting/notifying
+ * the last promise in the chain and listening on the first one, and
browsers have call stack
+ * limits low enough that we previously ran into them for files around
a couple hundred megabytes
+ * (the worst is Firefox 47 with a limit of 1024 calls).
+ *
+ * @param {File} file
+ * @return {jQuery.Promise} Promise which behaves identically to a
regular non-chunked upload
+ * promise from #upload
+ */
+ mw.FormDataTransport.prototype.chunkedUpload = function ( file ) {
+ var
+ offset,
+ prevPromise = $.Deferred().resolve(),
+ deferred = $.Deferred(),
+ fileSize = file.size,
+ chunkSize = this.chunkSize,
+ transport = this;
+
+ for ( offset = 0; offset < fileSize; offset += chunkSize ) {
+ /*jshint loopfunc:true */
+ // Capture offset in a closure
+ ( function ( offset ) {
+ var
+ newPromise = $.Deferred(),
+ isLastChunk = offset + chunkSize >=
fileSize,
+ thisChunkSize = isLastChunk ? (
fileSize % chunkSize ) : chunkSize;
+ prevPromise.done( function () {
+ transport.uploadChunk( file, offset )
+ .done( isLastChunk ?
deferred.resolve : newPromise.resolve )
+ .fail( deferred.reject )
+ .progress( function ( fraction
) {
+ // The progress
notifications give us per-chunk progress.
+ // Calculate progress
for the whole file.
+ deferred.notify( (
offset + fraction * thisChunkSize ) / fileSize );
+ } );
+ } );
+ prevPromise = newPromise;
+ } )( offset );
+ }
+
+ return deferred.promise();
};
/**
@@ -221,8 +257,7 @@
case 'Continue':
// Reset retry counter
transport.retries = 0;
- // Start uploading next chunk
- return transport.uploadChunk(
file, response.upload.offset );
+ /* falls through */
case 'Success':
// Just pass the response
through.
return response;
--
To view, visit https://gerrit.wikimedia.org/r/297347
To unsubscribe, visit https://gerrit.wikimedia.org/r/settings
Gerrit-MessageType: newchange
Gerrit-Change-Id: Ia34134f4aac58d80a2752efe8103fdf3646e6078
Gerrit-PatchSet: 1
Gerrit-Project: mediawiki/extensions/UploadWizard
Gerrit-Branch: master
Gerrit-Owner: Bartosz Dziewoński <[email protected]>
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