/* * QEMU buffered QEMUFile * * Copyright IBM, Corp. 2008 * * Authors: * Anthony Liguori * * This work is licensed under the terms of the GNU GPL, version 2. See * the COPYING file in the top-level directory. * * Contributions after 2012-01-13 are licensed under the terms of the * GNU GPL, version 2 or (at your option) any later version. */ #include "qemu-common.h" #include "hw/hw.h" #include "qemu-timer.h" #include "qemu-char.h" #include "buffered_file.h" //#define DEBUG_BUFFERED_FILE typedef struct QEMUFileBuffered { BufferedPutFunc *put_buffer; BufferedPutReadyFunc *put_ready; BufferedWaitForUnfreezeFunc *wait_for_unfreeze; BufferedCloseFunc *close; void *migration_state; QEMUFile *file; int freeze_output; size_t bytes_xfer; size_t xfer_limit; uint8_t *buffer; size_t buffer_size; size_t buffer_capacity; QEMUTimer *timer; } QEMUFileBuffered; #ifdef DEBUG_BUFFERED_FILE #define DPRINTF(fmt, ...) \ do { printf("buffered-file: " fmt, ## __VA_ARGS__); } while (0) #else #define DPRINTF(fmt, ...) \ do { } while (0) #endif static void buffered_append(QEMUFileBuffered *s, const uint8_t *buf, size_t size) { if (size > (s->buffer_capacity - s->buffer_size)) { DPRINTF("increasing buffer capacity from %zu by %zu\n", s->buffer_capacity, size + 1024); s->buffer_capacity += size + 1024; s->buffer = g_realloc(s->buffer, s->buffer_capacity); } memcpy(s->buffer + s->buffer_size, buf, size); s->buffer_size += size; } static void buffered_flush(QEMUFileBuffered *s) { size_t offset = 0; int error; error = qemu_file_get_error(s->file); if (error != 0) { DPRINTF("flush when error, bailing: %s\n", strerror(-error)); return; } DPRINTF("flushing %zu byte(s) of data\n", s->buffer_size); while (s->bytes_xfer < s->xfer_limit && offset < s->buffer_size) { ssize_t ret; ret = s->put_buffer(s->migration_state, s->buffer + offset, s->buffer_size - offset); if (ret == -EAGAIN) { DPRINTF("backend not ready, freezing\n"); s->freeze_output = 1; break; } if (ret <= 0) { DPRINTF("error flushing data, %zd\n", ret); qemu_file_set_error(s->file, ret); break; } else { DPRINTF("flushed %zd byte(s)\n", ret); offset += ret; s->bytes_xfer += ret; } } DPRINTF("flushed %zu of %zu byte(s)\n", offset, s->buffer_size); memmove(s->buffer, s->buffer + offset, s->buffer_size - offset); s->buffer_size -= offset; } static int buffered_put_buffer(void *opaque, const uint8_t *buf, int64_t pos, int size) { QEMUFileBuffered *s = opaque; int error; DPRINTF("putting %d bytes at %" PRId64 "\n", size, pos); error = qemu_file_get_error(s->file); if (error) { DPRINTF("flush when error, bailing: %s\n", strerror(-error)); return error; } DPRINTF("unfreezing output\n"); s->freeze_output = 0; if (size > 0) { DPRINTF("buffering %d bytes\n", size - offset); buffered_append(s, buf, size); } buffered_flush(s); if (pos == 0 && size == 0) { DPRINTF("file is ready\n"); if (!s->freeze_output && s->bytes_xfer < s->xfer_limit) { DPRINTF("notifying client\n"); s->put_ready(s->migration_state); } } return size; } static int buffered_close(void *opaque) { QEMUFileBuffered *s = opaque; int ret; DPRINTF("closing\n"); s->xfer_limit = INT_MAX; while (!qemu_file_get_error(s->file) && s->buffer_size) { buffered_flush(s); if (s->freeze_output) s->wait_for_unfreeze(s->migration_state); } ret = s->close(s->migration_state); qemu_del_timer(s->timer); qemu_free_timer(s->timer); g_free(s->buffer); g_free(s); return ret; } /* * The meaning of the return values is: * 0: We can continue sending * 1: Time to stop * negative: There has been an error */ static int buffered_rate_limit(void *opaque) { QEMUFileBuffered *s = opaque; int ret; ret = qemu_file_get_error(s->file); if (ret) { return ret; } if (s->freeze_output) return 1; if (s->bytes_xfer > s->xfer_limit) return 1; return 0; } static int64_t buffered_set_rate_limit(void *opaque, int64_t new_rate) { QEMUFileBuffered *s = opaque; if (qemu_file_get_error(s->file)) { goto out; } if (new_rate > SIZE_MAX) { new_rate = SIZE_MAX; } s->xfer_limit = new_rate / 10; out: return s->xfer_limit; } static int64_t buffered_get_rate_limit(void *opaque) { QEMUFileBuffered *s = opaque; return s->xfer_limit; } static void buffered_rate_tick(void *opaque) { QEMUFileBuffered *s = opaque; if (qemu_file_get_error(s->file)) { buffered_close(s); return; } qemu_mod_timer(s->timer, qemu_get_clock_ms(rt_clock) + 100); if (s->freeze_output) return; s->bytes_xfer = 0; buffered_put_buffer(s, NULL, 0, 0); } QEMUFile *qemu_fopen_ops_buffered(void *opaque, size_t bytes_per_sec, BufferedPutFunc *put_buffer, BufferedPutReadyFunc *put_ready, BufferedWaitForUnfreezeFunc *wait_for_unfreeze, BufferedCloseFunc *close) { QEMUFileBuffered *s; s = g_malloc0(sizeof(*s)); s->migration_state = opaque; s->xfer_limit = bytes_per_sec / 10; s->put_buffer = put_buffer; s->put_ready = put_ready; s->wait_for_unfreeze = wait_for_unfreeze; s->close = close; s->file = qemu_fopen_ops(s, buffered_put_buffer, NULL, buffered_close, buffered_rate_limit, buffered_set_rate_limit, buffered_get_rate_limit); s->timer = qemu_new_timer_ms(rt_clock, buffered_rate_tick, s); qemu_mod_timer(s->timer, qemu_get_clock_ms(rt_clock) + 100); return s->file; }