Perf: Optimize sending HTTP/2 frame

proxy/http2/HTTP2.cc

@@ -243,24 +243,6 @@ http2_write_frame_header(const Http2FrameHeader &hdr, IOVec iov)
   return true;
 }
 
-bool
-http2_write_data(const uint8_t *src, size_t length, const IOVec &iov)
-{
-  byte_pointer ptr(iov.iov_base);
-  write_and_advance(ptr, src, length);
-
-  return true;
-}
-
-bool
-http2_write_headers(const uint8_t *src, size_t length, const IOVec &iov)
-{
-  byte_pointer ptr(iov.iov_base);
-  write_and_advance(ptr, src, length);
-
-  return true;
-}
-
 bool
 http2_write_rst_stream(uint32_t error_code, IOVec iov)
 {

proxy/http2/HTTP2.h

@@ -33,6 +33,9 @@ class HTTPHdr;
 
 typedef unsigned Http2StreamId;
 
+constexpr Http2StreamId HTTP2_CONNECTION_CONTROL_STRTEAM = 0;
+constexpr uint8_t HTTP2_FRAME_NO_FLAG                    = 0;
+
 // [RFC 7540] 6.9.2. Initial Flow Control Window Size
 // the flow control window can be come negative so we need to track it with a signed type.
 typedef int32_t Http2WindowSize;
@@ -320,10 +323,6 @@ bool http2_parse_frame_header(IOVec, Http2FrameHeader &);
 
 bool http2_write_frame_header(const Http2FrameHeader &, IOVec);
 
-bool http2_write_data(const uint8_t *, size_t, const IOVec &);
-
-bool http2_write_headers(const uint8_t *, size_t, const IOVec &);
-
 bool http2_write_rst_stream(uint32_t, IOVec);
 
 bool http2_write_settings(const Http2SettingsParameter &, const IOVec &);

proxy/http2/Http2ClientSession.cc

@@ -213,7 +213,8 @@ Http2ClientSession::new_connection(NetVConnection *new_vc, MIOBuffer *iobuf, IOB
   this->read_buffer->water_mark = connection_state.server_settings.get(HTTP2_SETTINGS_MAX_FRAME_SIZE);
   this->_reader                 = reader ? reader : this->read_buffer->alloc_reader();
 
-  this->write_buffer = new_MIOBuffer(HTTP2_HEADER_BUFFER_SIZE_INDEX);
+  // Set write buffer size to max size of TLS record (16KB)
+  this->write_buffer = new_MIOBuffer(BUFFER_SIZE_INDEX_16K);
   this->sm_writer    = this->write_buffer->alloc_reader();
 
   this->_handle_if_ssl(new_vc);
@@ -332,6 +333,19 @@ Http2ClientSession::set_half_close_local_flag(bool flag)
   half_close_local = flag;
 }
 
+int64_t
+Http2ClientSession::xmit(const Http2TxFrame &frame)
+{
+  int64_t len = frame.write_to(this->write_buffer);
+
+  if (len > 0) {
+    total_write_len += len;
+    write_reenable();
+  }
+
+  return len;
+}
+
 int
 Http2ClientSession::main_event_handler(int event, void *edata)
 {
@@ -356,16 +370,6 @@ Http2ClientSession::main_event_handler(int event, void *edata)
     break;
   }
 
-  case HTTP2_SESSION_EVENT_XMIT: {
-    Http2Frame *frame = static_cast<Http2Frame *>(edata);
-    total_write_len += frame->size();
-    write_vio->nbytes = total_write_len;
-    frame->xmit(this->write_buffer);
-    write_reenable();
-    retval = 0;
-    break;
-  }
-
   case HTTP2_SESSION_EVENT_REENABLE:
     // VIO will be reenableed in this handler
     retval = (this->*session_handler)(VC_EVENT_READ_READY, static_cast<VIO *>(e->cookie));
@@ -391,6 +395,7 @@ Http2ClientSession::main_event_handler(int event, void *edata)
     retval = 0;
     break;
 
+  case HTTP2_SESSION_EVENT_XMIT:
   default:
     Http2SsnDebug("unexpected event=%d edata=%p", event, edata);
     ink_release_assert(0);

proxy/http2/Http2ClientSession.h

@@ -27,6 +27,7 @@
 #include "Plugin.h"
 #include "ProxySession.h"
 #include "Http2ConnectionState.h"
+#include "Http2Frame.h"
 #include <string_view>
 #include "tscore/ink_inet.h"
 #include "tscore/History.h"
@@ -77,96 +78,6 @@ struct Http2UpgradeContext {
   Http2ConnectionSettings client_settings;
 };
 
-class Http2Frame
-{
-public:
-  Http2Frame(const Http2FrameHeader &h, IOBufferReader *r, bool e = false) : hdr(h), ioreader(r), from_early_data(e) {}
-  Http2Frame(Http2FrameType type, Http2StreamId streamid, uint8_t flags, bool e = false)
-    : hdr({0, (uint8_t)type, flags, streamid}), from_early_data(e)
-  {
-  }
-
-  IOBufferReader *
-  reader() const
-  {
-    return ioreader;
-  }
-
-  const Http2FrameHeader &
-  header() const
-  {
-    return this->hdr;
-  }
-
-  // Allocate an IOBufferBlock for payload of this frame.
-  void
-  alloc(int index)
-  {
-    this->ioblock = new_IOBufferBlock();
-    this->ioblock->alloc(index);
-  }
-
-  // Return the writeable buffer space for frame payload
-  IOVec
-  write()
-  {
-    return make_iovec(this->ioblock->end(), this->ioblock->write_avail());
-  }
-
-  // Once the frame has been serialized, update the payload length of frame header.
-  void
-  finalize(size_t nbytes)
-  {
-    if (this->ioblock) {
-      ink_assert((int64_t)nbytes <= this->ioblock->write_avail());
-      this->ioblock->fill(nbytes);
-
-      this->hdr.length = this->ioblock->size();
-    }
-  }
-
-  void
-  xmit(MIOBuffer *iobuffer)
-  {
-    // Write frame header
-    uint8_t buf[HTTP2_FRAME_HEADER_LEN];
-    http2_write_frame_header(hdr, make_iovec(buf));
-    iobuffer->write(buf, sizeof(buf));
-
-    // Write frame payload
-    // It could be empty (e.g. SETTINGS frame with ACK flag)
-    if (ioblock && ioblock->read_avail() > 0) {
-      iobuffer->append_block(this->ioblock.get());
-    }
-  }
-
-  int64_t
-  size()
-  {
-    if (ioblock) {
-      return HTTP2_FRAME_HEADER_LEN + ioblock->size();
-    } else {
-      return HTTP2_FRAME_HEADER_LEN;
-    }
-  }
-
-  bool
-  is_from_early_data() const
-  {
-    return this->from_early_data;
-  }
-
-  // noncopyable
-  Http2Frame(Http2Frame &) = delete;
-  Http2Frame &operator=(const Http2Frame &) = delete;
-
-private:
-  Http2FrameHeader hdr;       // frame header
-  Ptr<IOBufferBlock> ioblock; // frame payload
-  IOBufferReader *ioreader = nullptr;
-  bool from_early_data     = false;
-};
-
 class Http2ClientSession : public ProxySession
 {
 public:
@@ -194,6 +105,7 @@ class Http2ClientSession : public ProxySession
 
   // more methods
   void write_reenable();
+  int64_t xmit(const Http2TxFrame &frame);
 
   ////////////////////
   // Accessors