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From sudhe...@apache.org
Subject [1/3] trafficserver git commit: [TS-4243] Collapsed Forwarding Plugin based on Open Write Fail Action feature.
Date Tue, 01 Mar 2016 15:31:08 GMT
Repository: trafficserver
Updated Branches:
  refs/heads/master 5731dbb80 -> 0861ec445


[TS-4243] Collapsed Forwarding Plugin based on Open Write Fail Action feature.

Clang format.

Made all internal methods and data "static" per @jpeach's suggestion.


Project: http://git-wip-us.apache.org/repos/asf/trafficserver/repo
Commit: http://git-wip-us.apache.org/repos/asf/trafficserver/commit/9e2c463a
Tree: http://git-wip-us.apache.org/repos/asf/trafficserver/tree/9e2c463a
Diff: http://git-wip-us.apache.org/repos/asf/trafficserver/diff/9e2c463a

Branch: refs/heads/master
Commit: 9e2c463ae4041c05d67a3c2a358fec7a7fabc67f
Parents: 5731dbb
Author: Sudheer Vinukonda <sudheerv@yahoo-inc.com>
Authored: Mon Feb 29 18:09:42 2016 +0000
Committer: Sudheer Vinukonda <sudheerv@yahoo-inc.com>
Committed: Mon Feb 29 18:33:49 2016 +0000

----------------------------------------------------------------------
 configure.ac                                    |   1 +
 .../collapsed_forwarding/Makefile.am            |  21 ++
 .../experimental/collapsed_forwarding/README    |  46 +++
 .../collapsed_forwarding.cc                     | 314 +++++++++++++++++++
 4 files changed, 382 insertions(+)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/trafficserver/blob/9e2c463a/configure.ac
----------------------------------------------------------------------
diff --git a/configure.ac b/configure.ac
index b9981a6..530d8c7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1942,6 +1942,7 @@ AC_CONFIG_FILES([
   plugins/experimental/generator/Makefile
   plugins/experimental/geoip_acl/Makefile
   plugins/experimental/header_normalize/Makefile
+  plugins/experimental/collapsed_forwarding/Makefile
   plugins/experimental/hipes/Makefile
   plugins/experimental/inliner/Makefile
   plugins/experimental/memcache/Makefile

http://git-wip-us.apache.org/repos/asf/trafficserver/blob/9e2c463a/plugins/experimental/collapsed_forwarding/Makefile.am
----------------------------------------------------------------------
diff --git a/plugins/experimental/collapsed_forwarding/Makefile.am b/plugins/experimental/collapsed_forwarding/Makefile.am
new file mode 100644
index 0000000..6e46a92
--- /dev/null
+++ b/plugins/experimental/collapsed_forwarding/Makefile.am
@@ -0,0 +1,21 @@
+#  Licensed to the Apache Software Foundation (ASF) under one
+#  or more contributor license agreements.  See the NOTICE file
+#  distributed with this work for additional information
+#  regarding copyright ownership.  The ASF licenses this file
+#  to you under the Apache License, Version 2.0 (the
+#  "License"); you may not use this file except in compliance
+#  with the License.  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+
+include $(top_srcdir)/build/plugins.mk
+
+pkglib_LTLIBRARIES = collapsed_forwarding.la
+collapsed_forwarding_la_SOURCES = collapsed_forwarding.cc
+collapsed_forwarding_la_LDFLAGS = $(TS_PLUGIN_LDFLAGS)

http://git-wip-us.apache.org/repos/asf/trafficserver/blob/9e2c463a/plugins/experimental/collapsed_forwarding/README
----------------------------------------------------------------------
diff --git a/plugins/experimental/collapsed_forwarding/README b/plugins/experimental/collapsed_forwarding/README
new file mode 100644
index 0000000..72fe545
--- /dev/null
+++ b/plugins/experimental/collapsed_forwarding/README
@@ -0,0 +1,46 @@
+////////////////////////////////////////////////////////////////////////////////
+// collapsed_forwarding::
+//
+// ATS plugin to allow collapsed forwarding of concurrent requests for the same
+// object. This plugin is based on open_write_fail_action feature, which detects
+// cache open write failure on a cache miss and returns a 502 error along with a
+// special @-header indicating the reason for 502 error. The plugin acts on the
+// error by using an internal redirect follow back to itself, essentially blocking
+// the request until a response arrives, at which point, relies on read-while-writer
+// feature to start downloading the object to all waiting clients. The following
+// config parameters are assumed to be set for this plugin to work:
+////////////////////////////////////////////////////////////////////////////////////
+// proxy.config.http.cache.open_write_fail_action        1 /////////////////////////
+// proxy.config.cache.enable_read_while_writer           1 /////////////////////////
+// proxy.config.http.redirection_enabled                 1 /////////////////////////
+// proxy.config.http.number_of_redirections             10 /////////////////////////
+// proxy.config.http.redirect_use_orig_cache_key         1 /////////////////////////
+// proxy.config.http.background_fill_active_timeout      0 /////////////////////////
+// proxy.config.http.background_fill_completed_threshold 0 /////////////////////////
+////////////////////////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////////////////////////////////////////
+// This plugin currently supports only per-remap mode activation.
+////////////////////////////////////////////////////////////////////////////////////
+
+More details are available at
+
+https://docs.trafficserver.apache.org/en/6.0.x/admin/http-proxy-caching.en.html#reducing-origin-server-requests-avoiding-the-thundering-herd
+
+Installation:
+
+    make
+    sudo make install
+
+If you don't have the traffic server binaries in your path, then you will need
+to specify the path to tsxs manually:
+
+    make TSXS=/opt/trafficserver/bin/tsxs
+    sudo make TSXS=/opt/trafficserver/bin/tsxs install
+
+Configuration:
+
+    Add @plugin=cache_range_requests.so to your remap.config rules.
+
+    Or for a global plugin where all range requests are processed,
+    Add cache_range_requests.so to the plugin.config
+

http://git-wip-us.apache.org/repos/asf/trafficserver/blob/9e2c463a/plugins/experimental/collapsed_forwarding/collapsed_forwarding.cc
----------------------------------------------------------------------
diff --git a/plugins/experimental/collapsed_forwarding/collapsed_forwarding.cc b/plugins/experimental/collapsed_forwarding/collapsed_forwarding.cc
new file mode 100644
index 0000000..5bd4e7b
--- /dev/null
+++ b/plugins/experimental/collapsed_forwarding/collapsed_forwarding.cc
@@ -0,0 +1,314 @@
+/** @file
+
+    Plugin to perform background fetches of certain content that would
+    otherwise not be cached. For example, Range: requests / responses.
+
+    @section license License
+
+    Licensed to the Apache Software Foundation (ASF) under one
+    or more contributor license agreements.  See the NOTICE file
+    distributed with this work for additional information
+    regarding copyright ownership.  The ASF licenses this file
+    to you under the Apache License, Version 2.0 (the
+    "License"); you may not use this file except in compliance
+    with the License.  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+*/
+
+////////////////////////////////////////////////////////////////////////////////
+// collapsed_forwarding::
+//
+// ATS plugin to allow collapsed forwarding of concurrent requests for the same
+// object. This plugin is based on open_write_fail_action feature, which detects
+// cache open write failure on a cache miss and returns a 502 error along with a
+// special @-header indicating the reason for 502 error. The plugin acts on the
+// error by using an internal redirect follow back to itself, essentially blocking
+// the request until a response arrives, at which point, relies on read-while-writer
+// feature to start downloading the object to all waiting clients. The following
+// config parameters are assumed to be set for this plugin to work:
+////////////////////////////////////////////////////////////////////////////////////
+// proxy.config.http.cache.open_write_fail_action        1 /////////////////////////
+// proxy.config.cache.enable_read_while_writer           1 /////////////////////////
+// proxy.config.http.redirection_enabled                 1 /////////////////////////
+// proxy.config.http.number_of_redirections             10 /////////////////////////
+// proxy.config.http.redirect_use_orig_cache_key         1 /////////////////////////
+// proxy.config.http.background_fill_active_timeout      0 /////////////////////////
+// proxy.config.http.background_fill_completed_threshold 0 /////////////////////////
+////////////////////////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////////////////////////////////////////
+// This plugin currently supports only per-remap mode activation.
+////////////////////////////////////////////////////////////////////////////////////
+
+#define UNUSED __attribute__((unused))
+static char UNUSED rcsId__collapsed_forwarding_cc[] =
+  "@(#) $Id: collapsed_forwarding.cc 218 2016-02-26 01:29:16Z sudheerv $ built on " __DATE__
" " __TIME__;
+
+
+#include <sys/time.h>
+#include <ts/ts.h>
+#include <ts/remap.h>
+#include <set>
+#include <string>
+#include <string.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <getopt.h>
+#include <netdb.h>
+#include <map>
+
+static const char *DEBUG_TAG = (char *)"collapsed_forwarding";
+
+static const char *LOCATION_HEADER = "Location";
+static const char *REDIRECT_REASON = "See Other";
+static const char *ATS_INTERNAL_MESSAGE = "@Ats-Internal";
+
+static int OPEN_WRITE_FAIL_MAX_REQ_DELAY_RETRIES = 5;
+static int OPEN_WRITE_FAIL_REQ_DELAY_TIMEOUT = 500;
+
+typedef struct _RequestData {
+  TSHttpTxn txnp;
+  int wl_retry; // write lock failure retry count
+  std::string req_url;
+} RequestData;
+
+static int
+add_redirect_header(TSMBuffer &bufp, TSMLoc &hdr_loc, const std::string &location)
+{
+  // This is needed in case the response already contains a Location header
+  TSMLoc field_loc = TSMimeHdrFieldFind(bufp, hdr_loc, LOCATION_HEADER, strlen(LOCATION_HEADER));
+
+  if (field_loc == TS_NULL_MLOC) {
+    TSMimeHdrFieldCreateNamed(bufp, hdr_loc, LOCATION_HEADER, strlen(LOCATION_HEADER), &field_loc);
+  }
+
+  if (TS_SUCCESS == TSMimeHdrFieldValueStringSet(bufp, hdr_loc, field_loc, -1, location.c_str(),
location.size())) {
+    TSDebug(DEBUG_TAG, "Adding Location header %s", LOCATION_HEADER);
+    TSMimeHdrFieldAppend(bufp, hdr_loc, field_loc);
+  }
+
+  TSHandleMLocRelease(bufp, hdr_loc, field_loc);
+
+  TSHttpHdrStatusSet(bufp, hdr_loc, TS_HTTP_STATUS_SEE_OTHER);
+  TSHttpHdrReasonSet(bufp, hdr_loc, REDIRECT_REASON, strlen(REDIRECT_REASON));
+  return TS_SUCCESS;
+}
+
+static bool
+check_internal_message_hdr(TSHttpTxn &txnp)
+{
+  TSMBuffer bufp;
+  TSMLoc hdr_loc;
+  bool found = false;
+
+  if (TSHttpTxnClientRespGet(txnp, &bufp, &hdr_loc) != TS_SUCCESS) {
+    TSError("check_internal_message_hdr: couldn't retrieve client response header");
+    return false;
+  }
+
+  TSMLoc header_loc = TSMimeHdrFieldFind(bufp, hdr_loc, ATS_INTERNAL_MESSAGE, strlen(ATS_INTERNAL_MESSAGE));
+  if (header_loc) {
+    found = true;
+    // found the header, remove it now..
+    TSMimeHdrFieldDestroy(bufp, hdr_loc, header_loc);
+    TSHandleMLocRelease(bufp, hdr_loc, header_loc);
+  }
+
+  TSHandleMLocRelease(bufp, TS_NULL_MLOC, hdr_loc);
+
+  return found;
+}
+
+static int
+on_OS_DNS(const RequestData *req, TSHttpTxn &txnp)
+{
+  if (req->wl_retry > 0) {
+    TSDebug(DEBUG_TAG, "OS_DNS request delayed %d times, block origin req for url: %s", req->wl_retry,
req->req_url.c_str());
+    TSHttpTxnReenable(txnp, TS_EVENT_HTTP_ERROR);
+    return TS_SUCCESS;
+  }
+
+  TSHttpTxnReenable(txnp, TS_EVENT_HTTP_CONTINUE);
+  return TS_SUCCESS;
+}
+
+static int
+on_send_request_header(const RequestData *req, TSHttpTxn &txnp)
+{
+  if (req->wl_retry > 0) {
+    TSDebug(DEBUG_TAG, "Send_Req request delayed %d times, block origin req for url: %s",
req->wl_retry, req->req_url.c_str());
+    TSHttpTxnReenable(txnp, TS_EVENT_HTTP_ERROR);
+    return TS_SUCCESS;
+  }
+
+  TSHttpTxnReenable(txnp, TS_EVENT_HTTP_CONTINUE);
+  return TS_SUCCESS;
+}
+
+static int
+on_read_response_header(TSHttpTxn &txnp)
+{
+  TSHttpTxnReenable(txnp, TS_EVENT_HTTP_CONTINUE);
+  return TS_SUCCESS;
+}
+
+static int
+on_immediate(RequestData *req, TSCont &contp)
+{
+  if (!req) {
+    TSError("%s: invalid req_data", DEBUG_TAG);
+    return TS_SUCCESS;
+  }
+
+  TSDebug(DEBUG_TAG, "continuation delayed, scheduling now..for url: %s", req->req_url.c_str());
+
+  // add retry_done header to prevent looping
+  std::string value;
+  TSMBuffer bufp;
+  TSMLoc hdr_loc;
+  if (TSHttpTxnClientRespGet(req->txnp, &bufp, &hdr_loc) != TS_SUCCESS) {
+    TSError("plugin=%s, level=error, error_code=could_not_retrieve_client_response_header
for url %s", DEBUG_TAG,
+            req->req_url.c_str());
+    TSHttpTxnReenable(req->txnp, TS_EVENT_HTTP_ERROR);
+    return TS_SUCCESS;
+  }
+
+  add_redirect_header(bufp, hdr_loc, req->req_url);
+  TSHandleMLocRelease(bufp, TS_NULL_MLOC, hdr_loc);
+  TSHttpTxnReenable(req->txnp, TS_EVENT_HTTP_CONTINUE);
+  return TS_SUCCESS;
+}
+
+static int
+on_send_response_header(RequestData *req, TSHttpTxn &txnp, TSCont &contp)
+{
+  TSMBuffer bufp;
+  TSMLoc hdr_loc;
+  if (TSHttpTxnClientRespGet(txnp, &bufp, &hdr_loc) != TS_SUCCESS) {
+    TSError("plugin=%s, level=error, error_code=could_not_retrieve_client_response_header",
DEBUG_TAG);
+    return TS_SUCCESS;
+  }
+
+  TSHttpStatus status = TSHttpHdrStatusGet(bufp, hdr_loc);
+  TSDebug(DEBUG_TAG, "Response code: %d", status);
+
+  if ((status == TS_HTTP_STATUS_BAD_GATEWAY) || (status == TS_HTTP_STATUS_SEE_OTHER)) {
+    bool is_internal_message_hdr = check_internal_message_hdr(txnp);
+    bool delay_request =
+      is_internal_message_hdr || ((req->wl_retry > 0) && (req->wl_retry
< OPEN_WRITE_FAIL_MAX_REQ_DELAY_RETRIES));
+
+    if (delay_request) {
+      req->wl_retry++;
+      TSDebug(DEBUG_TAG, "delaying request, url@%p: {{%s}} on retry: %d time", txnp, req->req_url.c_str(),
req->wl_retry);
+      TSContSchedule(contp, OPEN_WRITE_FAIL_REQ_DELAY_TIMEOUT, TS_THREAD_POOL_TASK);
+      TSHandleMLocRelease(bufp, TS_NULL_MLOC, hdr_loc);
+      return TS_SUCCESS;
+    }
+  }
+
+  if (req->wl_retry > 0) {
+    TSDebug(DEBUG_TAG, "request delayed, but unsuccessful, url@%p: {{%s}} on retry: %d time",
txnp, req->req_url.c_str(),
+            req->wl_retry);
+    req->wl_retry = 0;
+  }
+
+  // done..cleanup
+  TSfree(req);
+  TSContDestroy(contp);
+
+  TSHandleMLocRelease(bufp, TS_NULL_MLOC, hdr_loc);
+  TSHttpTxnReenable(txnp, TS_EVENT_HTTP_CONTINUE);
+  return TS_SUCCESS;
+}
+
+static int
+collapsed_cont(TSCont contp, TSEvent event, void *edata)
+{
+  TSHttpTxn txnp = static_cast<TSHttpTxn>(edata);
+  RequestData *my_req = static_cast<RequestData *>(TSContDataGet(contp));
+
+  switch (event) {
+  case TS_EVENT_HTTP_OS_DNS: {
+    return on_OS_DNS(my_req, txnp);
+  }
+
+  case TS_EVENT_HTTP_SEND_REQUEST_HDR: {
+    return on_send_request_header(my_req, txnp);
+  }
+
+  case TS_EVENT_HTTP_READ_RESPONSE_HDR: {
+    return on_read_response_header(txnp);
+  }
+  case TSEvent::TS_EVENT_IMMEDIATE:
+  case TSEvent::TS_EVENT_TIMEOUT: {
+    return on_immediate(my_req, contp);
+  }
+  case TS_EVENT_HTTP_SEND_RESPONSE_HDR: {
+    return on_send_response_header(my_req, txnp, contp);
+  }
+  default: {
+    TSDebug(DEBUG_TAG, "Unexpected event: %d", event);
+    break;
+  }
+  }
+
+  TSHttpTxnReenable(txnp, TS_EVENT_HTTP_CONTINUE);
+  return TS_SUCCESS;
+}
+
+TSReturnCode
+TSRemapInit(TSRemapInterface * /* api_info */, char * /* errbuf */, int /* errbuf_size */)
+{
+  TSDebug(DEBUG_TAG, "plugin is succesfully initialized");
+  return TS_SUCCESS;
+}
+
+TSReturnCode
+TSRemapNewInstance(int argc, char *argv[], void ** /* ih */, char * /* errbuf */, int /*
errbuf_size */)
+{
+  // basic argv processing..
+  for (int i = 2; i < argc; ++i) {
+    if (strncmp(argv[i], "--delay=", 8) == 0) {
+      OPEN_WRITE_FAIL_REQ_DELAY_TIMEOUT = atoi((char *)(argv[i] + 8));
+    } else if (strncmp(argv[i], "--retries=", 10) == 0) {
+      OPEN_WRITE_FAIL_MAX_REQ_DELAY_RETRIES = atoi((char *)(argv[i] + 10));
+    }
+  }
+
+  return TS_SUCCESS;
+}
+
+TSRemapStatus
+TSRemapDoRemap(void *ih, TSHttpTxn rh, TSRemapRequestInfo *rri)
+{
+  TSCont cont = TSContCreate(collapsed_cont, TSMutexCreate());
+
+  RequestData *req_data;
+  req_data = static_cast<RequestData *>(TSmalloc(sizeof(RequestData)));
+  memset(req_data, 0, sizeof(RequestData));
+
+  req_data->txnp = rh;
+  req_data->wl_retry = 0;
+
+  int url_len = 0;
+  char *url = TSHttpTxnEffectiveUrlStringGet(rh, &url_len);
+  req_data->req_url = std::string(url, url_len);
+
+  TSfree(url);
+  TSContDataSet(cont, req_data);
+
+  TSHttpTxnHookAdd(rh, TS_HTTP_SEND_REQUEST_HDR_HOOK, cont);
+  TSHttpTxnHookAdd(rh, TS_HTTP_SEND_RESPONSE_HDR_HOOK, cont);
+  TSHttpTxnHookAdd(rh, TS_HTTP_READ_RESPONSE_HDR_HOOK, cont);
+  TSHttpTxnHookAdd(rh, TS_HTTP_OS_DNS_HOOK, cont);
+
+  return TSREMAP_DID_REMAP;
+}


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