Cut unused AsyncSocket::isBufferMovable_

Summary: [Folly] Cut unused `AsyncSocket::isBufferMutovable_` and constants `SSL_MODE_MOVE_BUFFER_OWNERSHIP` and `kOpenSslModeMoveBufferOwnership`.

Reviewed By: w-o-o

Differential Revision: D19286264

fbshipit-source-id: 57e28e65cf86fd550fa8fe81e1657a2e9409e459

folly/io/async/AsyncSocket.cpp

@@ -2019,7 +2019,7 @@ void AsyncSocket::handleRead() noexcept {
           "non-exception type");
       return failRead(__func__, ex);
     }
-    if (!isBufferMovable_ && (buf == nullptr || buflen == 0)) {
+    if (buf == nullptr || buflen == 0) {
       AsyncSocketException ex(
           AsyncSocketException::BAD_ARGS,
           "ReadCallback::getReadBuffer() returned "
@@ -2033,18 +2033,7 @@ void AsyncSocket::handleRead() noexcept {
     VLOG(4) << "this=" << this << ", AsyncSocket::handleRead() got "
             << bytesRead << " bytes";
     if (bytesRead > 0) {
-      if (!isBufferMovable_) {
-        readCallback_->readDataAvailable(size_t(bytesRead));
-      } else {
-        CHECK(kOpenSslModeMoveBufferOwnership);
-        VLOG(5) << "this=" << this << ", AsyncSocket::handleRead() got "
-                << "buf=" << buf << ", " << bytesRead << "/" << buflen
-                << ", offset=" << offset;
-        auto readBuf = folly::IOBuf::takeOwnership(buf, buflen);
-        readBuf->trimStart(offset);
-        readBuf->trimEnd(buflen - offset - bytesRead);
-        readCallback_->readBufferAvailable(std::move(readBuf));
-      }
+      readCallback_->readDataAvailable(size_t(bytesRead));
 
       // Fall through and continue around the loop if the read
       // completely filled the available buffer.

folly/io/async/AsyncSocket.h

@@ -1294,8 +1294,6 @@ class AsyncSocket : virtual public AsyncTransportWrapper {
   uint32_t sendTimeout_; ///< The send timeout, in milliseconds
   uint16_t maxReadsPerEvent_; ///< Max reads per event loop iteration
 
-  bool isBufferMovable_{false};
-
   int8_t readErr_{READ_NO_ERROR}; ///< The read error encountered, if any
 
   EventBase* eventBase_; ///< The EventBase

folly/io/async/AsyncTransport.h

@@ -27,14 +27,6 @@
 #include <folly/portability/SysUio.h>
 #include <folly/ssl/OpenSSLPtrTypes.h>
 
-constexpr bool kOpenSslModeMoveBufferOwnership =
-#ifdef SSL_MODE_MOVE_BUFFER_OWNERSHIP
-    true
-#else
-    false
-#endif
-    ;
-
 namespace folly {
 
 class AsyncSocketException;