cfriedt commented on a change in pull request #2007:
URL: https://github.com/apache/thrift/pull/2007#discussion_r443396568
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File path: lib/cpp/src/thrift/transport/TBufferTransports.h
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@@ -587,11 +587,9 @@ class TMemoryBuffer : public
TVirtualTransport<TMemoryBuffer, TBufferBase> {
void resetBuffer() {
rBase_ = buffer_;
rBound_ = buffer_;
- wBase_ = buffer_;
- // It isn't safe to write into a buffer we don't own.
- if (!owner_) {
- wBound_ = wBase_;
- bufferSize_ = 0;
+ if (owner_) {
+ wBase_ = buffer_;
+ wBound_ = buffer_ + bufferSize_;
Review comment:
If the buffer is not owned (is read-only, i.e. was created with `policy
== OBSERVE`), `wBase_` is initialized to `wBase_ = buffer_ + wPos` (the end of
the buffer) inside of `initCommon()` and never updated.
Throughout the lifetime of the buffer, if it is not owned (read-only),
`wBound_ == wBase_`, meaning there is no space to write (both `wBound_` and
`wBase_` continue to point at the end of the buffer).
Only if the buffer is owned (writeable) should `wbase_` and `wbound_` be
reset to the beginning / end of the buffer, in `resetBuffer()`.
I agree, the current implementation is a bit confusing and it might be
possible to rewrite it to be more obvious. This change realizes the intent of
the design while keeping changes to the implementation minimal.
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