Remove IOBufQueue::clear()

Summary: All usages in fbsource have been removed.

Reviewed By: yfeldblum, philippv

Differential Revision: D33007671

fbshipit-source-id: 74c5f2dad098c6b7cf7085aa1a2e01a48fa81781

folly/io/IOBufQueue.cpp

@@ -395,19 +395,6 @@ std::unique_ptr<folly::IOBuf> IOBufQueue::pop_front() {
   return retBuf;
 }
 
-void IOBufQueue::clear() {
-  if (!head_) {
-    return;
-  }
-  auto guard = updateGuard();
-  IOBuf* buf = head_.get();
-  do {
-    buf->clear();
-    buf = buf->next();
-  } while (buf != head_.get());
-  chainLength_ = 0;
-}
-
 void IOBufQueue::clearAndTryReuseLargestBuffer() {
   auto guard = updateGuard();
   std::unique_ptr<folly::IOBuf> best;

folly/io/IOBufQueue.h

@@ -517,17 +517,6 @@ class IOBufQueue {
 
   const Options& options() const { return options_; }
 
-  /**
-   * Clear the queue.  Note that this does not release the buffers, it
-   * just sets their length to zero; useful if you want to reuse the
-   * same queue without reallocating.
-   *
-   * DEPRECATED: If the queue is chained, only the last buffer will actually be
-   * reused. In most cases, reset() should be used instead, or if reuse is
-   * intended, clearAndTryReuseLargestBuffer().
-   */
-  void clear();
-
   /**
    * Clear the queue, freeing all the buffers. Options are preserved.
    */