buffered_file.c

   1 /*
   2  * QEMU buffered QEMUFile
   3  *
   4  * Copyright IBM, Corp. 2008
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  * Contributions after 2012-01-13 are licensed under the terms of the
  13  * GNU GPL, version 2 or (at your option) any later version.
  14  */
  15
  16 #include "qemu-common.h"
  17 #include "hw/hw.h"
  18 #include "qemu/timer.h"
  19 #include "buffered_file.h"
  20 #include "qemu/thread.h"
  21
  22 //#define DEBUG_BUFFERED_FILE
  23
  24 typedef struct QEMUFileBuffered
  25 {
  26     MigrationState *migration_state;
  27     QEMUFile *file;
  28     size_t bytes_xfer;
  29     size_t xfer_limit;
  30     uint8_t *buffer;
  31     size_t buffer_size;
  32     size_t buffer_capacity;
  33     QemuThread thread;
  34 } QEMUFileBuffered;
  35
  36 #ifdef DEBUG_BUFFERED_FILE
  37 #define DPRINTF(fmt, ...) \
  38     do { printf("buffered-file: " fmt, ## __VA_ARGS__); } while (0)
  39 #else
  40 #define DPRINTF(fmt, ...) \
  41     do { } while (0)
  42 #endif
  43
  44 static void buffered_append(QEMUFileBuffered *s,
  45                             const uint8_t *buf, size_t size)
  46 {
  47     if (size > (s->buffer_capacity - s->buffer_size)) {
  48         DPRINTF("increasing buffer capacity from %zu by %zu\n",
  49                 s->buffer_capacity, size + 1024);
  50
  51         s->buffer_capacity += size + 1024;
  52
  53         s->buffer = g_realloc(s->buffer, s->buffer_capacity);
  54     }
  55
  56     memcpy(s->buffer + s->buffer_size, buf, size);
  57     s->buffer_size += size;
  58 }
  59
  60 static ssize_t buffered_flush(QEMUFileBuffered *s)
  61 {
  62     size_t offset = 0;
  63     ssize_t ret = 0;
  64
  65     DPRINTF("flushing %zu byte(s) of data\n", s->buffer_size);
  66
  67     while (s->bytes_xfer < s->xfer_limit && offset < s->buffer_size) {
  68         size_t to_send = MIN(s->buffer_size - offset, s->xfer_limit - s->bytes_xfer);
  69         ret = migrate_fd_put_buffer(s->migration_state, s->buffer + offset,
  70                                     to_send);
  71         if (ret <= 0) {
  72             DPRINTF("error flushing data, %zd\n", ret);
  73             break;
  74         } else {
  75             DPRINTF("flushed %zd byte(s)\n", ret);
  76             offset += ret;
  77             s->bytes_xfer += ret;
  78         }
  79     }
  80
  81     DPRINTF("flushed %zu of %zu byte(s)\n", offset, s->buffer_size);
  82     memmove(s->buffer, s->buffer + offset, s->buffer_size - offset);
  83     s->buffer_size -= offset;
  84
  85     if (ret < 0) {
  86         return ret;
  87     }
  88     return offset;
  89 }
  90
  91 static int buffered_put_buffer(void *opaque, const uint8_t *buf, int64_t pos, int size)
  92 {
  93     QEMUFileBuffered *s = opaque;
  94     ssize_t error;
  95
  96     DPRINTF("putting %d bytes at %" PRId64 "\n", size, pos);
  97
  98     error = qemu_file_get_error(s->file);
  99     if (error) {
 100         DPRINTF("flush when error, bailing: %s\n", strerror(-error));
 101         return error;
 102     }
 103
 104     if (size > 0) {
 105         DPRINTF("buffering %d bytes\n", size - offset);
 106         buffered_append(s, buf, size);
 107     }
 108
 109     error = buffered_flush(s);
 110     if (error < 0) {
 111         DPRINTF("buffered flush error. bailing: %s\n", strerror(-error));
 112         return error;
 113     }
 114
 115     if (pos == 0 && size == 0) {
 116         DPRINTF("file is ready\n");
 117         if (s->bytes_xfer < s->xfer_limit) {
 118             DPRINTF("notifying client\n");
 119             migrate_fd_put_ready(s->migration_state);
 120         }
 121     }
 122
 123     return size;
 124 }
 125
 126 static int buffered_close(void *opaque)
 127 {
 128     QEMUFileBuffered *s = opaque;
 129     ssize_t ret = 0;
 130     int ret2;
 131
 132     DPRINTF("closing\n");
 133
 134     s->xfer_limit = INT_MAX;
 135     while (!qemu_file_get_error(s->file) && s->buffer_size) {
 136         ret = buffered_flush(s);
 137         if (ret < 0) {
 138             break;
 139         }
 140     }
 141
 142     ret2 = migrate_fd_close(s->migration_state);
 143     if (ret >= 0) {
 144         ret = ret2;
 145     }
 146     ret = migrate_fd_close(s->migration_state);
 147     s->migration_state->complete = true;
 148     return ret;
 149 }
 150
 151 /*
 152  * The meaning of the return values is:
 153  *   0: We can continue sending
 154  *   1: Time to stop
 155  *   negative: There has been an error
 156  */
 157 static int buffered_get_fd(void *opaque)
 158 {
 159     QEMUFileBuffered *s = opaque;
 160
 161     return qemu_get_fd(s->file);
 162 }
 163
 164 static int buffered_rate_limit(void *opaque)
 165 {
 166     QEMUFileBuffered *s = opaque;
 167     int ret;
 168
 169     ret = qemu_file_get_error(s->file);
 170     if (ret) {
 171         return ret;
 172     }
 173
 174     if (s->bytes_xfer > s->xfer_limit)
 175         return 1;
 176
 177     return 0;
 178 }
 179
 180 static int64_t buffered_set_rate_limit(void *opaque, int64_t new_rate)
 181 {
 182     QEMUFileBuffered *s = opaque;
 183     if (qemu_file_get_error(s->file)) {
 184         goto out;
 185     }
 186     if (new_rate > SIZE_MAX) {
 187         new_rate = SIZE_MAX;
 188     }
 189
 190     s->xfer_limit = new_rate / 10;
 191
 192 out:
 193     return s->xfer_limit;
 194 }
 195
 196 static int64_t buffered_get_rate_limit(void *opaque)
 197 {
 198     QEMUFileBuffered *s = opaque;
 199
 200     return s->xfer_limit;
 201 }
 202
 203 /* 10ms  xfer_limit is the limit that we should write each 10ms */
 204 #define BUFFER_DELAY 100
 205
 206 static void *buffered_file_thread(void *opaque)
 207 {
 208     QEMUFileBuffered *s = opaque;
 209     int64_t expire_time = qemu_get_clock_ms(rt_clock) + BUFFER_DELAY;
 210
 211     while (true) {
 212         int64_t current_time = qemu_get_clock_ms(rt_clock);
 213
 214         if (s->migration_state->complete) {
 215             break;
 216         }
 217         if (current_time >= expire_time) {
 218             s->bytes_xfer = 0;
 219             expire_time = current_time + BUFFER_DELAY;
 220         }
 221         if (s->bytes_xfer >= s->xfer_limit) {
 222             /* usleep expects microseconds */
 223             g_usleep((expire_time - current_time)*1000);
 224         }
 225         buffered_put_buffer(s, NULL, 0, 0);
 226     }
 227     g_free(s->buffer);
 228     g_free(s);
 229     return NULL;
 230 }
 231
 232 static const QEMUFileOps buffered_file_ops = {
 233     .get_fd =         buffered_get_fd,
 234     .put_buffer =     buffered_put_buffer,
 235     .close =          buffered_close,
 236     .rate_limit =     buffered_rate_limit,
 237     .get_rate_limit = buffered_get_rate_limit,
 238     .set_rate_limit = buffered_set_rate_limit,
 239 };
 240
 241 void qemu_fopen_ops_buffered(MigrationState *migration_state)
 242 {
 243     QEMUFileBuffered *s;
 244
 245     s = g_malloc0(sizeof(*s));
 246
 247     s->migration_state = migration_state;
 248     s->xfer_limit = migration_state->bandwidth_limit / 10;
 249     s->migration_state->complete = false;
 250
 251     s->file = qemu_fopen_ops(s, &buffered_file_ops);
 252
 253     migration_state->file = s->file;
 254
 255     qemu_thread_create(&s->thread, buffered_file_thread, s,
 256                        QEMU_THREAD_DETACHED);
 257 }