[PATCH 6/7] trace: disable key after write error

From: Jeff King <peff@peff.net>
Date: Aug 3, 2016, 23:01 UTC
Message-ID: <20160803230103.daexq233ufrttnmn@sigill.intra.peff.net>
In-Reply-To: <20160803225600.fgm23bdacunmrw44@sigill.intra.peff.net>

If we get a write error writing to a trace descriptor, the error isn't likely to go away if we keep writing. Instead, you'll just get the same error over and over. E.g., try:

  GIT_TRACE_PACKET=42 git ls-remote >/dev/null

You don't really need to see:

  warning: unable to write trace for GIT_TRACE_PACKET: Bad file descriptor

hundreds of times. We could fallback to tracing to stderr, as we do in the error code-path for open(), but there's not much point. If the user fed us a bogus descriptor, they're probably better off fixing their invocation. And if they didn't, and we saw a transient error (e.g., ENOSPC writing to a file), it probably doesn't help anybody to have half of the trace in a file, and half on stderr.

Signed-off-by: Jeff King <peff@peff.net>
---
 trace.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/trace.c b/trace.c
index 4efb256..083eb98 100644
--- a/trace.c
+++ b/trace.c
@@ -134,6 +134,7 @@ static void trace_write(struct trace_key *key, const void *buf, unsigned len)
 		normalize_trace_key(&key);
 		warning("unable to write trace for %s: %s",
 			key->key, strerror(errno));
+		trace_disable(key);
 	}
 }

-- 
2.9.2.670.g42e63de