src/comm/IoCallback.h

   1 #ifndef _SQUID_COMM_IOCALLBACK_H
   2 #define _SQUID_COMM_IOCALLBACK_H
   3
   4 #include "base/AsyncCall.h"
   5 #include "comm/forward.h"
   6 #include "comm_err_t.h"
   7 #include "typedefs.h"
   8
   9 class SBuf;
  10
  11 namespace Comm
  12 {
  13
  14 /// Type of IO callbacks the Comm layer deals with.
  15 typedef enum {
  16     IOCB_NONE,
  17     IOCB_READ,
  18     IOCB_WRITE
  19 } iocb_type;
  20
  21 /// Details about a particular Comm IO callback event.
  22 class IoCallback
  23 {
  24 public:
  25     iocb_type type;
  26     Comm::ConnectionPointer conn;
  27     AsyncCall::Pointer callback;
  28
  29     /// Buffer to store read(2) into when set.
  30     // This is a pointer to the Jobs buffer rather than an SBuf using
  31     // the same store since we cannot know when or how the Job will
  32     // alter its SBuf while we are reading.
  33     SBuf *buf2;
  34
  35     // Legacy c-string buffers used when buf2 is unset.
  36     char *buf;
  37     FREE *freefunc;
  38     int size;
  39     int offset;
  40     comm_err_t errcode;
  41     int xerrno;
  42 #if USE_DELAY_POOLS
  43     unsigned int quotaQueueReserv; ///< reservation ID from CommQuotaQueue
  44 #endif
  45
  46     bool active() const { return callback != NULL; }
  47     void setCallback(iocb_type type, AsyncCall::Pointer &cb, char *buf, FREE *func, int sz);
  48
  49     /// called when fd needs to write but may need to wait in line for its quota
  50     void selectOrQueueWrite();
  51
  52     /// Actively cancel the given callback
  53     void cancel(const char *reason);
  54
  55     /// finish the IO operation imediately and schedule the callback with the current state.
  56     void finish(comm_err_t code, int xerrn);
  57
  58 private:
  59     void reset();
  60 };
  61
  62 /// Entry nodes for the IO callback table: iocb_table
  63 /// Keyed off the FD which the event applies to.
  64 class CbEntry
  65 {
  66 public:
  67     int fd;
  68     IoCallback  readcb;
  69     IoCallback  writecb;
  70 };
  71
  72 /// Table of scheduled IO events which have yet to be processed ??
  73 /// Callbacks which might be scheduled in future are stored in fd_table.
  74 extern CbEntry *iocb_table;
  75
  76 void CallbackTableInit();
  77 void CallbackTableDestruct();
  78
  79 #define COMMIO_FD_READCB(fd)    (&Comm::iocb_table[(fd)].readcb)
  80 #define COMMIO_FD_WRITECB(fd)   (&Comm::iocb_table[(fd)].writecb)
  81
  82 } // namespace Comm
  83
  84 #endif /* _SQUID_COMM_IOCALLBACK_H */