src/Pipeline.h

   1 /*
   2  * Copyright (C) 1996-2016 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 #ifndef SQUID_SRC_PIPELINE_H
  10 #define SQUID_SRC_PIPELINE_H
  11
  12 #include "base/RefCount.h"
  13
  14 #include <list>
  15
  16 class ClientSocketContext;
  17 typedef RefCount<ClientSocketContext> ClientSocketContextPointer;
  18
  19 /**
  20  * A queue of transactions awaiting completion.
  21  *
  22  * Transactions in the queue may be fully processed, but not yet delivered,
  23  * or only partially processed.
  24  *
  25  * - HTTP/1 pipelined requests can be processed out of order but
  26  *   responses MUST be written to the client in-order.
  27  *   The front() context is for the response writing transaction.
  28  *   The back context may still be reading a request payload/body.
  29  *   Other contexts are in deferred I/O state, but may be accumulating
  30  *   payload/body data to be written later.
  31  *
  32  * - HTTP/2 multiplexed streams can be processed and delivered in any order.
  33  *
  34  * For consistency we treat the pipeline as a FIFO queue in both cases.
  35  */
  36 class Pipeline
  37 {
  38     Pipeline(const Pipeline &) = delete;
  39     Pipeline & operator =(const Pipeline &) = delete;
  40
  41 public:
  42     Pipeline() : nrequests(0) {}
  43     ~Pipeline() = default;
  44
  45     /// register a new request context to the pipeline
  46     void add(const ClientSocketContextPointer &);
  47
  48     /// get the first request context in the pipeline
  49     ClientSocketContextPointer front() const;
  50
  51     /// how many requests are currently pipelined
  52     size_t count() const {return requests.size();}
  53
  54     /// whether there are none or any requests currently pipelined
  55     bool empty() const {return requests.empty();}
  56
  57     /// tell everybody about the err, and abort all waiting requests
  58     void terminateAll(const int xerrno);
  59
  60     /// deregister the front request from the pipeline
  61     void popMe(const ClientSocketContextPointer &);
  62
  63     /// Number of requests seen in this pipeline (so far).
  64     /// Includes incomplete transactions.
  65     uint32_t nrequests;
  66
  67 private:
  68     /// requests parsed from the connection but not yet completed.
  69     std::list<ClientSocketContextPointer> requests;
  70 };
  71
  72 #endif /* SQUID_SRC_PIPELINE_H */
  73