src/comm/IoCallback.h

   1 /*
   2  * Copyright (C) 1996-2023 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_COMM_IOCALLBACK_H
  10 #define _SQUID_COMM_IOCALLBACK_H
  11
  12 #include "base/AsyncCall.h"
  13 #include "comm/Flag.h"
  14 #include "comm/forward.h"
  15 #include "mem/forward.h"
  16 #include "sbuf/forward.h"
  17
  18 namespace Comm
  19 {
  20
  21 /// Type of IO callbacks the Comm layer deals with.
  22 typedef enum {
  23     IOCB_NONE,
  24     IOCB_READ,
  25     IOCB_WRITE
  26 } iocb_type;
  27
  28 /// Details about a particular Comm IO callback event.
  29 class IoCallback
  30 {
  31 public:
  32     iocb_type type;
  33     Comm::ConnectionPointer conn;
  34     AsyncCall::Pointer callback;
  35     char *buf;
  36     FREE *freefunc;
  37     int size;
  38     int offset;
  39     Comm::Flag errcode;
  40     int xerrno;
  41 #if USE_DELAY_POOLS
  42     unsigned int quotaQueueReserv; ///< reservation ID from CommQuotaQueue
  43 #endif
  44
  45     bool active() const { return callback != nullptr; }
  46     void setCallback(iocb_type type, AsyncCall::Pointer &cb, char *buf, FREE *func, int sz);
  47
  48     /// called when fd needs to write but may need to wait in line for its quota
  49     void selectOrQueueWrite();
  50
  51     /// Actively cancel the given callback
  52     void cancel(const char *reason);
  53
  54     /// finish the IO operation immediately and schedule the callback with the current state.
  55     void finish(Comm::Flag code, int xerrn);
  56
  57 private:
  58     void reset();
  59 };
  60
  61 /// Entry nodes for the IO callback table: iocb_table
  62 /// Keyed off the FD which the event applies to.
  63 class CbEntry
  64 {
  65 public:
  66     int fd;
  67     IoCallback  readcb;
  68     IoCallback  writecb;
  69 };
  70
  71 /// Table of scheduled IO events which have yet to be processed ??
  72 /// Callbacks which might be scheduled in future are stored in fd_table.
  73 extern CbEntry *iocb_table;
  74
  75 void CallbackTableInit();
  76 void CallbackTableDestruct();
  77
  78 #define COMMIO_FD_READCB(fd)    (&Comm::iocb_table[(fd)].readcb)
  79 #define COMMIO_FD_WRITECB(fd)   (&Comm::iocb_table[(fd)].writecb)
  80
  81 } // namespace Comm
  82
  83 #endif /* _SQUID_COMM_IOCALLBACK_H */
  84