plugins/experimental/rate_limit/txn_limiter.h

/*
 * 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.
 */
#pragma once

#include "limiter.h"
#include "ts/ts.h"

///////////////////////////////////////////////////////////////////////////////
// TXN based limiters, for remap.config plugin instances.
//
class TxnRateLimiter : public RateLimiter<TSHttpTxn>
{
public:
  TxnRateLimiter() { Dbg(dbg_ctl, "Creating txn rate limiter"); }

  ~TxnRateLimiter() override
  {
    Dbg(dbg_ctl, "Destroying txn rate limiter");
    if (_action) {
      TSActionCancel(_action);
    }
    if (_queue_cont) {
      TSContDestroy(_queue_cont);
    }
  }

  void setupTxnCont(TSHttpTxn txnp, TSHttpHookID hook);
  void setupSsnCont(TSHttpSsn ssnp);
  bool initialize(int argc, const char *argv[]);

  const std::string &
  header() const
  {
    return _header;
  }

  unsigned
  error() const
  {
    return _error;
  }

  unsigned
  retry() const
  {
    return _retry;
  }

  bool
  conntrack() const
  {
    return _conntrack;
  }

private:
  std::string _header    = "";    // Header to put the latency metrics in, e.g. @RateLimit-Delay
  unsigned    _error     = 429;   // Error code when we decide not to allow a txn to be processed (e.g. queue full)
  unsigned    _retry     = 0;     // If > 0, we will also send a Retry-After: header with this retry value
  bool        _conntrack = false; // If true, we will track connections and limit based on that instead of transactions

  TSCont   _queue_cont = nullptr; // Continuation processing the queue periodically
  TSAction _action     = nullptr; // The action associated with the queue continuation, needed to shut it down
};