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zlib: emit "close" if Z_STREAM_END occurs. #3747

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Yi EungJun Isaac Z. Schlueter Nodejs Jenkins Fedor Indutny
Yi EungJun
npcode commented

In src/node_zlib.cc, Z_OK, Z_STREAM_END and Z_BUF_ERROR has been ignored because they are considered normal statuses.

But Z_STREAM_END must be handled. Even if zlib does not end when it meets Z_STREAM_END, it should at least tell user so that user can stop it.

(Actaully, I believe "end" is better than "close" for this case, but emitting "end" may cause exception because zlib does not allow to write something to itself if zlib._ended is true.)

Isaac Z. Schlueter
Collaborator
isaacs commented

This isn't quite accurate.

Z_STREAM_END is the return value if all the output is consumed, and the flush param was set to Z_FINISH. However, the "close" event should be used only when the underlying resource is completely disposed of (ie, when deflateEnd or inflateEnd has been successfully called to free the memory.) This would occur when the binding has been deleted, but we don't actually track that, and just let that happen when V8's garbage collector cleans things up.

However, upon receiving a Z_STREAM_END, you can call .reset() on the stream, and then re-use it again. In fact, this is a useful way to prevent having to create new underlying objects.

What we probably ought to do is remove the place where we're currently emitting "end", and only emit "end" when a Z_STREAM_END return value is encountered. Would you like to change your patch to do that?

Yi EungJun npcode zlib: Emit "end" instead of "close" for Z_STREAM_END
Emit "end" instead of "close" when Z_STREAM_END return value is
encountered. And remove emitting "end" in Zlib.end().
3efc532
Yi EungJun
npcode commented

You are right, @isaacs . I have done as you said and it looks to work well.

Nodejs Jenkins
Collaborator

Can one of the admins verify this patch?

Fedor Indutny
Collaborator

I guess it isn't relevant anymore?

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Showing 2 unique commits by 1 author.

Jul 20, 2012
Yi EungJun npcode zlib: emit "close" if Z_STREAM_END occurs. 45cb346
Yi EungJun npcode zlib: Emit "end" instead of "close" for Z_STREAM_END
Emit "end" instead of "close" when Z_STREAM_END return value is
encountered. And remove emitting "end" in Zlib.end().
3efc532
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Showing 2 changed files with 7 additions and 3 deletions. Show diff stats Hide diff stats

  1. +5 2 lib/zlib.js
  2. +2 1  src/node_zlib.cc
7 lib/zlib.js
@@ -346,7 +346,6 @@ Zlib.prototype.end = function end(chunk, cb) {
346 346 var self = this;
347 347 this._ending = true;
348 348 var ret = this.write(chunk, function() {
349   - self.emit('end');
350 349 if (cb) cb();
351 350 });
352 351 this._ended = true;
@@ -392,7 +391,7 @@ Zlib.prototype._process = function() {
392 391 req.callback = callback;
393 392 this._processing = req;
394 393
395   - function callback(availInAfter, availOutAfter, buffer) {
  394 + function callback(err, availInAfter, availOutAfter, buffer) {
396 395 if (self._hadError) return;
397 396
398 397 var have = availOutBefore - availOutAfter;
@@ -438,6 +437,10 @@ Zlib.prototype._process = function() {
438 437 self._processing = false;
439 438 if (cb) cb();
440 439 self._process();
  440 +
  441 + if (err == binding.Z_STREAM_END) {
  442 + self.emit('end');
  443 + }
441 444 }
442 445 };
443 446
3  src/node_zlib.cc
@@ -211,7 +211,8 @@ class ZCtx : public ObjectWrap {
211 211 // call the write() cb
212 212 assert(ctx->handle_->Get(callback_sym)->IsFunction() &&
213 213 "Invalid callback");
214   - Local<Value> args[2] = { avail_in, avail_out };
  214 + Local<Value> args[3] = { Local<Value>::New(Number::New(ctx->err_)),
  215 + avail_in, avail_out };
215 216 MakeCallback(ctx->handle_, callback_sym, ARRAY_SIZE(args), args);
216 217
217 218 ctx->Unref();

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