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From zw...@apache.org
Subject [2/6] trafficserver git commit: TS-3505 Basic plugin to provide finer granularity over cache writes
Date Fri, 24 Apr 2015 14:06:06 GMT
TS-3505 Basic plugin to provide finer granularity over cache writes


Project: http://git-wip-us.apache.org/repos/asf/trafficserver/repo
Commit: http://git-wip-us.apache.org/repos/asf/trafficserver/commit/a196c201
Tree: http://git-wip-us.apache.org/repos/asf/trafficserver/tree/a196c201
Diff: http://git-wip-us.apache.org/repos/asf/trafficserver/diff/a196c201

Branch: refs/heads/master
Commit: a196c2019b2cb50585f2b9b98d7dd35db4c693e9
Parents: 231f11e
Author: Leif Hedstrom <zwoop@apache.org>
Authored: Tue Apr 7 22:04:24 2015 -0600
Committer: Leif Hedstrom <zwoop@apache.org>
Committed: Fri Apr 24 07:57:56 2015 -0600

----------------------------------------------------------------------
 configure.ac                                    |   1 +
 plugins/experimental/Makefile.am                |   1 +
 plugins/experimental/cache_promote/Makefile.am  |  21 ++
 .../experimental/cache_promote/cache_promote.cc | 259 +++++++++++++++++++
 plugins/experimental/cache_promote/lulu.h       |  35 +++
 5 files changed, 317 insertions(+)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/trafficserver/blob/a196c201/configure.ac
----------------------------------------------------------------------
diff --git a/configure.ac b/configure.ac
index 9cb71b3..11405e3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1946,6 +1946,7 @@ AS_IF([test "x$enable_experimental_plugins" = xyes], [
     plugins/experimental/balancer/Makefile
     plugins/experimental/buffer_upload/Makefile
     plugins/experimental/channel_stats/Makefile
+    plugins/experimental/cache_promote/Makefile
     plugins/experimental/collapsed_connection/Makefile
     plugins/experimental/custom_redirect/Makefile
     plugins/experimental/epic/Makefile

http://git-wip-us.apache.org/repos/asf/trafficserver/blob/a196c201/plugins/experimental/Makefile.am
----------------------------------------------------------------------
diff --git a/plugins/experimental/Makefile.am b/plugins/experimental/Makefile.am
index 2ef296c..552df97 100644
--- a/plugins/experimental/Makefile.am
+++ b/plugins/experimental/Makefile.am
@@ -19,6 +19,7 @@ SUBDIRS = \
  background_fetch \
  balancer \
  buffer_upload \
+ cache_promote \
  channel_stats \
  collapsed_connection \
  custom_redirect \

http://git-wip-us.apache.org/repos/asf/trafficserver/blob/a196c201/plugins/experimental/cache_promote/Makefile.am
----------------------------------------------------------------------
diff --git a/plugins/experimental/cache_promote/Makefile.am b/plugins/experimental/cache_promote/Makefile.am
new file mode 100644
index 0000000..8170aed
--- /dev/null
+++ b/plugins/experimental/cache_promote/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 = cache_promote.la
+cache_promote_la_SOURCES = cache_promote.cc
+cache_promote_la_LDFLAGS = $(TS_PLUGIN_LDFLAGS)

http://git-wip-us.apache.org/repos/asf/trafficserver/blob/a196c201/plugins/experimental/cache_promote/cache_promote.cc
----------------------------------------------------------------------
diff --git a/plugins/experimental/cache_promote/cache_promote.cc b/plugins/experimental/cache_promote/cache_promote.cc
new file mode 100644
index 0000000..e2934ad
--- /dev/null
+++ b/plugins/experimental/cache_promote/cache_promote.cc
@@ -0,0 +1,259 @@
+/*
+  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.
+*/
+
+
+//////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Main entry points for the plugin hooks etc.
+//
+#include <ts/ts.h>
+#include <ts/remap.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "lulu.h"
+
+
+// Virtual base class for all policies
+class PromotionPolicy
+{
+public:
+  virtual ~PromotionPolicy(){};
+  virtual bool parseArguments(int argc, char *argv[]) = 0;
+  virtual bool doPromote(TSHttpTxn txnp) const = 0;
+
+  const char *
+  getPolicyName() const
+  {
+    return _policy_name;
+  }
+
+  void
+  usage()
+  {
+    TSDebug(PLUGIN_NAME, "Usage: @plugin=%s.so @pparam=%s @pparam=<n>%%", PLUGIN_NAME,
getPolicyName());
+    TSError("Usage: @plugin=%s.so @pparam=%s @pparam=<n>%%", PLUGIN_NAME, getPolicyName());
+  }
+
+private:
+  const char *_policy_name = "virtual";
+};
+
+
+// This is the simplest of all policies, just give each request a (small)
+// percentage chance to be promoted to cache. Usage:
+//
+//   @plugin=cache_promot.so @pparam=chance @pparam=10%
+class ChancePolicy : public PromotionPolicy
+{
+public:
+  ChancePolicy() : _percent(0.0)
+  {
+    // This doesn't have to be perfect, since this is just statistical sampling.
+    // coverity[dont_call]
+    srand48((long)time(NULL));
+  }
+
+  bool
+  parseArguments(int argc, char *argv[])
+  {
+    if (4 != argc) {
+      usage();
+      return false;
+    }
+
+    _percent = strtof(argv[3], NULL) / 100.0;
+    if (_percent < 0 || _percent > 1) {
+      usage();
+      return false;
+    }
+
+    TSDebug(PLUGIN_NAME, "created remap rule, with chance policy of %s (%f)", argv[3], _percent);
+    return true;
+  }
+
+
+  bool doPromote(TSHttpTxn /* txnp ATS_UNUSED */) const
+  {
+    double r = drand48();
+
+    TSDebug(PLUGIN_NAME, "evaluating ChancePolicy::doPromote(), %f > %f ?", _percent,
r);
+    // coverity[dont_call]
+    return _percent > r;
+  }
+
+private:
+  float _percent;
+  const char *_policy_name = "chance";
+};
+
+
+// This holds the configuration for a remap rule
+class PromotionConfig
+{
+public:
+  PromotionConfig() : _policy(NULL){};
+
+  ~PromotionConfig() { delete _policy; }
+
+  const PromotionPolicy *
+  getPolicy() const
+  {
+    return _policy;
+  }
+
+  // Parse the command line arguments to the plugin, and instantiate the appropriate policy
+  bool
+  factory(int argc, char *argv[])
+  {
+    if (argc < 3) {
+      TSError("Unable to create remap instance, need a percentage parameter");
+      return false;
+    }
+
+    if (0 == strncasecmp(argv[2], "chance", 6)) {
+      _policy = new ChancePolicy();
+    } else {
+      TSError("Unknown policy: %s", argv[2]);
+      return false;
+    }
+
+    if (!_policy->parseArguments(argc, argv)) {
+      delete _policy;
+      _policy = NULL;
+      return false;
+    }
+
+    return true;
+  }
+
+private:
+  PromotionPolicy *_policy;
+};
+
+
+//////////////////////////////////////////////////////////////////////////////
+// Main "plugin", a TXN hook in the TS_HTTP_READ_CACHE_HDR_HOOK. Unless the
+// policy allows caching, we will turn off the cache from here on for the TXN.
+//
+static int
+cont_handle_policy(TSCont contp, TSEvent event, void *edata)
+{
+  // ToDo: If we want to support per-remap configurations, we have to pass along the data
here
+  TSHttpTxn txnp = static_cast<TSHttpTxn>(edata);
+  PromotionConfig *config = static_cast<PromotionConfig *>(TSContDataGet(contp));
+  int obj_status;
+
+  switch (event) {
+  case TS_EVENT_HTTP_CACHE_LOOKUP_COMPLETE:
+    if (TS_ERROR != TSHttpTxnCacheLookupStatusGet(txnp, &obj_status)) {
+      switch (obj_status) {
+      case TS_CACHE_LOOKUP_MISS:
+      case TS_CACHE_LOOKUP_SKIPPED:
+        if (!config->getPolicy()->doPromote(txnp)) {
+          TSDebug(PLUGIN_NAME, "cache-status is %d, and turning off the cache (not promoted)",
obj_status);
+          TSHttpTxnHookAdd(txnp, TS_HTTP_READ_RESPONSE_HDR_HOOK, contp);
+        } else {
+          TSDebug(PLUGIN_NAME, "cache-status is %d, and leaving cache on (promoted)", obj_status);
+        }
+        break;
+      default:
+        // Do nothing, just let it handle the lookup.
+        TSDebug(PLUGIN_NAME, "cache hit, so leaving it alone");
+        break;
+      }
+    }
+    break;
+
+  case TS_EVENT_HTTP_READ_RESPONSE_HDR:
+    TSHttpTxnServerRespNoStoreSet(txnp, 1);
+    break;
+
+  default:
+    TSDebug(PLUGIN_NAME, "Unhandled event %d", (int)event);
+    break;
+  }
+
+  // Reenable and continue with the state machine.
+  TSHttpTxnReenable(txnp, TS_EVENT_HTTP_CONTINUE);
+  return 0;
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
+// Initialize the plugin as a remap plugin.
+//
+TSReturnCode
+TSRemapInit(TSRemapInterface *api_info, char *errbuf, int errbuf_size)
+{
+  if (api_info->size < sizeof(TSRemapInterface)) {
+    strncpy(errbuf, "[tsremap_init] - Incorrect size of TSRemapInterface structure", errbuf_size
- 1);
+    return TS_ERROR;
+  }
+
+  if (api_info->tsremap_version < TSREMAP_VERSION) {
+    snprintf(errbuf, errbuf_size - 1, "[tsremap_init] - Incorrect API version %ld.%ld", api_info->tsremap_version
>> 16,
+             (api_info->tsremap_version & 0xffff));
+    return TS_ERROR;
+  }
+
+  TSDebug(PLUGIN_NAME, "remap plugin is successfully initialized");
+  return TS_SUCCESS; /* success */
+}
+
+
+TSReturnCode
+TSRemapNewInstance(int argc, char *argv[], void **ih, char * /* errbuf */, int /* errbuf_size
*/)
+{
+  PromotionConfig *config = new PromotionConfig;
+  TSCont contp = TSContCreate(cont_handle_policy, TSMutexCreate());
+
+  config->factory(argc, argv);
+  TSContDataSet(contp, static_cast<void *>(config));
+  *ih = static_cast<void *>(contp);
+
+  return TS_SUCCESS;
+}
+
+void
+TSRemapDeleteInstance(void *ih)
+{
+  TSCont contp = static_cast<TSCont>(ih);
+  PromotionConfig *config = static_cast<PromotionConfig *>(TSContDataGet(contp));
+
+  delete config;
+  TSContDestroy(contp);
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
+// Schedule the cache-read continuation for this remap rule.
+//
+TSRemapStatus
+TSRemapDoRemap(void *ih, TSHttpTxn rh, TSRemapRequestInfo * /* ATS_UNUSED rri */)
+{
+  if (NULL == ih) {
+    TSDebug(PLUGIN_NAME, "No ACLs configured, this is probably a plugin bug");
+  } else {
+    TSCont contp = static_cast<TSCont>(ih);
+
+    TSHttpTxnHookAdd(rh, TS_HTTP_CACHE_LOOKUP_COMPLETE_HOOK, contp);
+  }
+
+  return TSREMAP_NO_REMAP;
+}

http://git-wip-us.apache.org/repos/asf/trafficserver/blob/a196c201/plugins/experimental/cache_promote/lulu.h
----------------------------------------------------------------------
diff --git a/plugins/experimental/cache_promote/lulu.h b/plugins/experimental/cache_promote/lulu.h
new file mode 100644
index 0000000..7ef866f
--- /dev/null
+++ b/plugins/experimental/cache_promote/lulu.h
@@ -0,0 +1,35 @@
+/*
+  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.
+*/
+
+
+//////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Implement the classes for the various types of hash keys we support.
+//
+#ifndef __LULU_H__
+#define __LULU_H__ 1
+
+#include <sys/types.h>
+
+#include "ink_defs.h"
+#include "ink_atomic.h"
+
+// Used for Debug etc.
+static const char *PLUGIN_NAME = "cache_promote";
+
+#endif // __LULU_H__


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