[Libguestfs] [nbdkit PATCH 3/4] filters: Utilize ACQUIRE_LOCK_FOR_CURRENT_SCOPE

[Eric Blake]

Now that cleanup.h is in common code, we can use it in our filters
where it makes sense. Many uses of pthread_mutex_unlock() are not
function-wide, and over small enough snippets of code as to be easier
to read when left as-is; but when the scope is indeed function-wide or
across multiple exit paths, it is nicer to use the macro for automatic
unlock.

Signed-off-by: Eric Blake <eblake at redhat.com>
---
 filters/log/log.c             | 10 ++++------
 filters/readahead/readahead.c | 15 +++++----------
 filters/log/Makefile.am       |  5 ++++-
 filters/readahead/Makefile.am |  5 ++++-
 4 files changed, 17 insertions(+), 18 deletions(-)

diff --git a/filters/log/log.c b/filters/log/log.c
index 02a2522..513d390 100644
--- a/filters/log/log.c
+++ b/filters/log/log.c
@@ -45,6 +45,8 @@

 #include <nbdkit-filter.h>

+#include "cleanup.h"
+
 #define THREAD_MODEL NBDKIT_THREAD_MODEL_PARALLEL

 static uint64_t connections;
@@ -114,12 +116,8 @@ struct handle {
 static uint64_t
 get_id (struct handle *h)
 {
-  uint64_t r;
-
-  pthread_mutex_lock (&lock);
-  r = ++h->id;
-  pthread_mutex_unlock (&lock);
-  return r;
+  ACQUIRE_LOCK_FOR_CURRENT_SCOPE(&lock);
+  return ++h->id;
 }

 /* Output a timestamp and the log message. */
diff --git a/filters/readahead/readahead.c b/filters/readahead/readahead.c
index 5e14347..f46b6b0 100644
--- a/filters/readahead/readahead.c
+++ b/filters/readahead/readahead.c
@@ -42,6 +42,7 @@

 #include <nbdkit-filter.h>

+#include "cleanup.h"
 #include "minmax.h"

 #define THREAD_MODEL NBDKIT_THREAD_MODEL_PARALLEL
@@ -150,7 +151,7 @@ readahead_pread (struct nbdkit_next_ops *next_ops, void *nxdata,
                  void *handle, void *buf, uint32_t count, uint64_t offset,
                  uint32_t flags, int *err)
 {
-  pthread_mutex_lock (&lock);
+  ACQUIRE_LOCK_FOR_CURRENT_SCOPE (&lock);

   while (count > 0) {
     if (length == 0) {
@@ -159,7 +160,7 @@ readahead_pread (struct nbdkit_next_ops *next_ops, void *nxdata,
        */
       window = READAHEAD_MIN;
       if (fill_readahead (next_ops, nxdata, count, offset, flags, err) == -1)
-        goto err;
+        return -1;
     }

     /* Can we satisfy this request partly or entirely from the prefetch
@@ -179,7 +180,7 @@ readahead_pread (struct nbdkit_next_ops *next_ops, void *nxdata,
     else if (offset == position + length) {
       window = MIN (window * 2, READAHEAD_MAX);
       if (fill_readahead (next_ops, nxdata, count, offset, flags, err) == -1)
-        goto err;
+        return -1;
     }

     /* Else it's a “miss”.  Reset everything and start again. */
@@ -187,12 +188,7 @@ readahead_pread (struct nbdkit_next_ops *next_ops, void *nxdata,
       length = 0;
   }

-  pthread_mutex_unlock (&lock);
   return 0;
-
- err:
-  pthread_mutex_unlock (&lock);
-  return -1;
 }

 /* Any writes or write-like operations kill the prefetch buffer.
@@ -204,10 +200,9 @@ readahead_pread (struct nbdkit_next_ops *next_ops, void *nxdata,
 static void
 kill_readahead (void)
 {
-  pthread_mutex_lock (&lock);
+  ACQUIRE_LOCK_FOR_CURRENT_SCOPE (&lock);
   window = READAHEAD_MIN;
   length = 0;
-  pthread_mutex_unlock (&lock);
 }

 static int
diff --git a/filters/log/Makefile.am b/filters/log/Makefile.am
index 271d54e..08cdd00 100644
--- a/filters/log/Makefile.am
+++ b/filters/log/Makefile.am
@@ -40,12 +40,15 @@ nbdkit_log_filter_la_SOURCES = \
 	$(top_srcdir)/include/nbdkit-filter.h

 nbdkit_log_filter_la_CPPFLAGS = \
-	-I$(top_srcdir)/include
+	-I$(top_srcdir)/include \
+	-I$(top_srcdir)/common/utils
 nbdkit_log_filter_la_CFLAGS = \
 	$(WARNINGS_CFLAGS)
 nbdkit_log_filter_la_LDFLAGS = \
 	-module -avoid-version -shared \
 	-Wl,--version-script=$(top_srcdir)/filters/filters.syms
+nbdkit_log_filter_la_LIBADD = \
+	$(top_builddir)/common/utils/libutils.la

 if HAVE_POD

diff --git a/filters/readahead/Makefile.am b/filters/readahead/Makefile.am
index 0e7a4a8..54adfb8 100644
--- a/filters/readahead/Makefile.am
+++ b/filters/readahead/Makefile.am
@@ -41,12 +41,15 @@ nbdkit_readahead_filter_la_SOURCES = \

 nbdkit_readahead_filter_la_CPPFLAGS = \
 	-I$(top_srcdir)/include \
-	-I$(top_srcdir)/common/include
+	-I$(top_srcdir)/common/include \
+	-I$(top_srcdir)/common/utils
 nbdkit_readahead_filter_la_CFLAGS = \
 	$(WARNINGS_CFLAGS)
 nbdkit_readahead_filter_la_LDFLAGS = \
 	-module -avoid-version -shared \
 	-Wl,--version-script=$(top_srcdir)/filters/filters.syms
+nbdkit_readahead_filter_la_LIBADD = \
+	$(top_builddir)/common/utils/libutils.la

 if HAVE_POD

-- 
2.20.1