[PATCH] libecasoundc: retry eci_impl_fd_read() even if poll timeout (was: Re: eci_init() fails on MIPS)

Alessandro Ghedini <[email protected]> Fri, 31 Jan 2014 12:33:28 +0100

Newsgroups	gmane.comp.audio.ecasound.general
Message-ID	<20140131113328.GA2103@kronk>

On Thu, Jan 30, 2014 at 11:05:24PM +0200, Kai Vehmanen wrote:
> Hi,
> 
> On Sun, 26 Jan 2014, Alessandro Ghedini wrote:
> >the eci_init() function in libecasoundc doesn't seem to work on MIPS. The
> >following test case fails:
> 
> this will launch a ecasound process on the background and try to
> connect to it via a pipe. Perhaps the executable cannot be started.

Nope, ecasound gets started correctly.

> You could try run the test program with "ECASOUND_LOGFILE=log.txt
> ./test" or try to "strace -f ./test" to figure out what's going
> wrong.

This is the relevant part (when the error occurs):

[...]
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 754373473}) = 0
9068  <... poll resumed> )              = 0 (Timeout)
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 756334781}) = 0
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 756537710}) = 0
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 756738400}) = 0
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 756939884}) = 0
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 757140772}) = 0
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 757342496}) = 0
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 757544092}) = 0
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 757745677}) = 0
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 757947137}) = 0
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 758148795}) = 0
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 758349873}) = 0
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 758551329}) = 0
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 758752200}) = 0
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 758954256}) = 0
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 759155872}) = 0
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 759357456}) = 0
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 759559136}) = 0
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 759760719}) = 0
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 759962259}) = 0
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 760202002}) = 0
9068  write(2, "\n(ecasoundc_sa) Error='read() error', cmd='' last_error='' cmd_cnt=1 last_cnt=0.\n", 81) = 81
9068  brk(0x85e000)                     = 0x85e000
9070  clock_gettime(CLOCK_MONOTONIC, {1721804, 764930227}) = 0
[...]

(9070 is ecasound, 9068 is the test case). You can get the full trace at [0].

So, if I read the trace correctly, it appears that the poll timeout used in
eci_impl_fd_read() expires before ecasound is ready, which in turn makes
eci_impl_read_return_value() fail.

So, a possible solution would be to retry the eci_impl_fd_read() even if the
timeout has expired. That part of the code is already run in a loop for, at
most, ECI_MAX_RESYNC_ATTEMPTS times, so there should be no risk in getting stuck
there.

See the attached patch (I already verified that it fixes the problem).

Cheers

[0] http://bugs.debian.org/cgi-bin/bugreport.cgi?msg=76;filename=trace.xz;att=1;bug=736616

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0001-libecasoundc-retry-eci_impl_fd_read-even-if-poll-tim.patch (text/x-diff, 824 B)

From e78b87b59b5e8b9a40843fc726e7ee7059a7134e Mon Sep 17 00:00:00 2001
From: Alessandro Ghedini <[email protected]>
Date: Fri, 31 Jan 2014 00:22:21 +0100
Subject: [PATCH] libecasoundc: retry eci_impl_fd_read() even if poll timeout
 has expired

---
 libecasoundc/ecasoundc_sa.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/libecasoundc/ecasoundc_sa.c b/libecasoundc/ecasoundc_sa.c
index 7692cae..bbe736b 100644
--- a/libecasoundc/ecasoundc_sa.c
+++ b/libecasoundc/ecasoundc_sa.c
@@ -1041,8 +1041,6 @@ static void eci_impl_read_return_value(struct eci_internal* eci_rep, int timeout
     else {
       if (res < 0) {
 	ECI_DEBUG_1("(ecasoundc_sa) timeout when reading return values (attempts=%d)!\n", attempts);
-	eci_rep->parser_repp->sync_lost_rep = true;
-	break;
       }
     }
     ++attempts;
-- 
1.9.rc1

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