grep: assert that threading is enabled when calling grep_{lock,unlock}

Change the grep_{lock,unlock} functions to assert that num_threads is
true, instead of only locking & unlocking the pthread mutex lock when
it is.

These functions are never called when num_threads isn't true, this
logic has gone through multiple iterations since the initial
introduction of grep threading in commit 5b594f457a ("Threaded grep",
2010-01-25), but ever since then they'd only be called if num_threads
was true, so this check made the code confusing to read.

Replace the check with an assertion, so that it's clear to the reader
that this code path is never taken unless we're spawning threads.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/grep.c b/builtin/grep.c
index 3c721b75a51b57be4d54380f80458693f33bdc51..b1095362fbf9a4726367b96e0f34d38faf27d9bd 100644 (file)
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -73,14 +73,14 @@ static pthread_mutex_t grep_mutex;
 
 static inline void grep_lock(void)
 {
-       if (num_threads)
-               pthread_mutex_lock(&grep_mutex);
+       assert(num_threads);
+       pthread_mutex_lock(&grep_mutex);
 }
 
 static inline void grep_unlock(void)
 {
-       if (num_threads)
-               pthread_mutex_unlock(&grep_mutex);
+       assert(num_threads);
+       pthread_mutex_unlock(&grep_mutex);
 }
 
 /* Signalled when a new work_item is added to todo. */