Hey, Avery Pennarun wrote: > On Tue, Nov 10, 2009 at 8:48 AM, Robert Jordan <robe...@gmx.net> wrote: >> MemoryStream.GetBuffer's docs indirectly suggest that no copy >> will be performed: >> >> "Note that the buffer contains allocated bytes which might be unused. >> For example, if the string "test" is written into the MemoryStream >> object, the length of the buffer returned from GetBuffer is 256, not 4, >> with 252 bytes unused. To obtain only the data in the buffer, use the >> ToArray method; however, ToArray creates a copy of the data in memory." >> >> So MemoryStream.GetBuffer must remain an O(1) operation in any case, >> defeating any kind of optimization a chunked memory stream >> implementation may introduce. > > Although this might be strictly true if you want to react exactly as > Microsoft's documentation claims (I thought 100% compatibility with > .Net was not the primary goal of mono?), there may be other options > that result in similar performance
Right, but MemoryStream is pretty prevalent and one of its frequent usage pattern is: var ms = new MemoryStream () or MemoryStream(somepredictedsize); // fill ms with some stream APIs ms.Close (); var bytes = ms.GetBuffer (); // pass `bytes' to byte[] APIs (e.g. unmanaged world) > For example, the first call to GetBuffer() could "coagulate" the > chunks into a single big array (perhaps with extra space at the end), > and then *keep that array*. Subsequent calls to GetBuffer() could > avoid the copy. GetBuffer () is usually called only once per instance. Robert _______________________________________________ Mono-devel-list mailing list Mono-devel-list@lists.ximian.com http://lists.ximian.com/mailman/listinfo/mono-devel-list
