src/comm/Write.cc

   1 #include "squid.h"
   2 #if USE_DELAY_POOLS
   3 #include "ClientInfo.h"
   4 #endif
   5 #include "comm/Connection.h"
   6 #include "comm/IoCallback.h"
   7 #include "comm/Write.h"
   8 #include "fde.h"
   9 #include "StatCounters.h"
  10 #include "SquidTime.h"
  11 #include "MemBuf.h"
  12
  13 void
  14 Comm::Write(const Comm::ConnectionPointer &conn, MemBuf *mb, AsyncCall::Pointer &callback)
  15 {
  16     Comm::Write(conn, mb->buf, mb->size, callback, mb->freeFunc());
  17 }
  18
  19 void
  20 Comm::Write(const Comm::ConnectionPointer &conn, const char *buf, int size, AsyncCall::Pointer &callback, FREE * free_func)
  21 {
  22     debugs(5, 5, HERE << conn << ": sz " << size << ": asynCall " << callback);
  23
  24     /* Make sure we are open, not closing, and not writing */
  25     assert(fd_table[conn->fd].flags.open);
  26     assert(!fd_table[conn->fd].closing());
  27     Comm::IoCallback *ccb = COMMIO_FD_WRITECB(conn->fd);
  28     assert(!ccb->active());
  29
  30     fd_table[conn->fd].writeStart = squid_curtime;
  31     ccb->conn = conn;
  32     /* Queue the write */
  33     ccb->setCallback(IOCB_WRITE, callback, (char *)buf, free_func, size);
  34     ccb->selectOrQueueWrite();
  35 }
  36
  37 /** Write to FD.
  38  * This function is used by the lowest level of IO loop which only has access to FD numbers.
  39  * We have to use the comm iocb_table to map FD numbers to waiting data and Comm::Connections.
  40  * Once the write has been concluded we schedule the waiting call with success/fail results.
  41  */
  42 void
  43 Comm::HandleWrite(int fd, void *data)
  44 {
  45     Comm::IoCallback *state = static_cast<Comm::IoCallback *>(data);
  46     int len = 0;
  47     int nleft;
  48
  49     assert(state->conn != NULL && state->conn->fd == fd);
  50
  51     PROF_start(commHandleWrite);
  52     debugs(5, 5, HERE << state->conn << ": off " <<
  53            (long int) state->offset << ", sz " << (long int) state->size << ".");
  54
  55     nleft = state->size - state->offset;
  56
  57 #if USE_DELAY_POOLS
  58     ClientInfo * clientInfo=fd_table[fd].clientInfo;
  59
  60     if (clientInfo && !clientInfo->writeLimitingActive)
  61         clientInfo = NULL; // we only care about quota limits here
  62
  63     if (clientInfo) {
  64         assert(clientInfo->selectWaiting);
  65         clientInfo->selectWaiting = false;
  66
  67         assert(clientInfo->hasQueue());
  68         assert(clientInfo->quotaPeekFd() == fd);
  69         clientInfo->quotaDequeue(); // we will write or requeue below
  70
  71         if (nleft > 0) {
  72             const int quota = clientInfo->quotaForDequed();
  73             if (!quota) {  // if no write quota left, queue this fd
  74                 state->quotaQueueReserv = clientInfo->quotaEnqueue(fd);
  75                 clientInfo->kickQuotaQueue();
  76                 PROF_stop(commHandleWrite);
  77                 return;
  78             }
  79
  80             const int nleft_corrected = min(nleft, quota);
  81             if (nleft != nleft_corrected) {
  82                 debugs(5, 5, HERE << state->conn << " writes only " <<
  83                        nleft_corrected << " out of " << nleft);
  84                 nleft = nleft_corrected;
  85             }
  86
  87         }
  88     }
  89 #endif /* USE_DELAY_POOLS */
  90
  91     /* actually WRITE data */
  92     len = FD_WRITE_METHOD(fd, state->buf + state->offset, nleft);
  93     debugs(5, 5, HERE << "write() returns " << len);
  94
  95 #if USE_DELAY_POOLS
  96     if (clientInfo) {
  97         if (len > 0) {
  98             /* we wrote data - drain them from bucket */
  99             clientInfo->bucketSize -= len;
 100             if (clientInfo->bucketSize < 0.0) {
 101                 debugs(5,1, HERE << "drained too much"); // should not happen
 102                 clientInfo->bucketSize = 0;
 103             }
 104         }
 105
 106         // even if we wrote nothing, we were served; give others a chance
 107         clientInfo->kickQuotaQueue();
 108     }
 109 #endif /* USE_DELAY_POOLS */
 110
 111     fd_bytes(fd, len, FD_WRITE);
 112     ++statCounter.syscalls.sock.writes;
 113     // After each successful partial write,
 114     // reset fde::writeStart to the current time.
 115     fd_table[fd].writeStart = squid_curtime;
 116
 117     if (len == 0) {
 118         /* Note we even call write if nleft == 0 */
 119         /* We're done */
 120         if (nleft != 0)
 121             debugs(5, DBG_IMPORTANT, "FD " << fd << " write failure: connection closed with " << nleft << " bytes remaining.");
 122
 123         state->finish(nleft ? COMM_ERROR : COMM_OK, errno);
 124     } else if (len < 0) {
 125         /* An error */
 126         if (fd_table[fd].flags.socket_eof) {
 127             debugs(50, 2, HERE << "FD " << fd << " write failure: " << xstrerror() << ".");
 128             state->finish(nleft ? COMM_ERROR : COMM_OK, errno);
 129         } else if (ignoreErrno(errno)) {
 130             debugs(50, 9, HERE << "FD " << fd << " write failure: " << xstrerror() << ".");
 131             state->selectOrQueueWrite();
 132         } else {
 133             debugs(50, 2, HERE << "FD " << fd << " write failure: " << xstrerror() << ".");
 134             state->finish(nleft ? COMM_ERROR : COMM_OK, errno);
 135         }
 136     } else {
 137         /* A successful write, continue */
 138         state->offset += len;
 139
 140         if (state->offset < state->size) {
 141             /* Not done, reinstall the write handler and write some more */
 142             state->selectOrQueueWrite();
 143         } else {
 144             state->finish(nleft ? COMM_OK : COMM_ERROR, errno);
 145         }
 146     }
 147
 148     PROF_stop(commHandleWrite);
 149 }