buffer: add tracing

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Peter Lieven <pl@kamp.de>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 1446203414-4013-7-git-send-email-kraxel@redhat.com

trace-events

@@ -1387,6 +1387,12 @@ ppc_tb_adjust(uint64_t offs1, uint64_t offs2, int64_t diff, int64_t seconds) "ad
 prep_io_800_writeb(uint32_t addr, uint32_t val) "0x%08" PRIx32 " => 0x%02" PRIx32
 prep_io_800_readb(uint32_t addr, uint32_t retval) "0x%08" PRIx32 " <= 0x%02" PRIx32
 
+# io/buffer.c
+buffer_resize(const char *buf, size_t olen, size_t len) "%s: old %zd, new %zd"
+buffer_move_empty(const char *buf, size_t len, const char *from) "%s: %zd bytes from %s"
+buffer_move(const char *buf, size_t len, const char *from) "%s: %zd bytes from %s"
+buffer_free(const char *buf, size_t len) "%s: capacity %zd"
+
 # util/hbitmap.c
 hbitmap_iter_skip_words(const void *hb, void *hbi, uint64_t pos, unsigned long cur) "hb %p hbi %p pos %"PRId64" cur 0x%lx"
 hbitmap_reset(void *hb, uint64_t start, uint64_t count, uint64_t sbit, uint64_t ebit) "hb %p items %"PRIu64",%"PRIu64" bits %"PRIu64"..%"PRIu64

util/buffer.c

@@ -19,6 +19,7 @@
  */
 
 #include "qemu/buffer.h"
+#include "trace.h"
 
 #define BUFFER_MIN_INIT_SIZE     4096
 #define BUFFER_MIN_SHRINK_SIZE  65536
@@ -34,6 +35,8 @@ void buffer_init(Buffer *buffer, const char *name, ...)
 
 void buffer_shrink(Buffer *buffer)
 {
+    size_t old;
+
     /*
      * Only shrink in case the used size is *much* smaller than the
      * capacity, to avoid bumping up & down the buffers all the time.
@@ -44,17 +47,25 @@ void buffer_shrink(Buffer *buffer)
         return;
     }
 
+    old = buffer->capacity;
     buffer->capacity = pow2ceil(buffer->offset);
     buffer->capacity = MAX(buffer->capacity, BUFFER_MIN_SHRINK_SIZE);
     buffer->buffer = g_realloc(buffer->buffer, buffer->capacity);
+    trace_buffer_resize(buffer->name ?: "unnamed",
+                        old, buffer->capacity);
 }
 
 void buffer_reserve(Buffer *buffer, size_t len)
 {
+    size_t old;
+
     if ((buffer->capacity - buffer->offset) < len) {
+        old = buffer->capacity;
         buffer->capacity = pow2ceil(buffer->offset + len);
         buffer->capacity = MAX(buffer->capacity, BUFFER_MIN_INIT_SIZE);
         buffer->buffer = g_realloc(buffer->buffer, buffer->capacity);
+        trace_buffer_resize(buffer->name ?: "unnamed",
+                            old, buffer->capacity);
     }
 }
 
@@ -75,6 +86,7 @@ void buffer_reset(Buffer *buffer)
 
 void buffer_free(Buffer *buffer)
 {
+    trace_buffer_free(buffer->name ?: "unnamed", buffer->capacity);
     g_free(buffer->buffer);
     g_free(buffer->name);
     buffer->offset = 0;
@@ -98,6 +110,9 @@ void buffer_advance(Buffer *buffer, size_t len)
 
 void buffer_move_empty(Buffer *to, Buffer *from)
 {
+    trace_buffer_move_empty(to->name ?: "unnamed",
+                            from->offset,
+                            from->name ?: "unnamed");
     assert(to->offset == 0);
 
     g_free(to->buffer);
@@ -117,6 +132,9 @@ void buffer_move(Buffer *to, Buffer *from)
         return;
     }
 
+    trace_buffer_move(to->name ?: "unnamed",
+                      from->offset,
+                      from->name ?: "unnamed");
     buffer_reserve(to, from->offset);
     buffer_append(to, from->buffer, from->offset);