Re: [libvirt] [PATCH 2/2] log: drain log of exiting qemu process carefully

Read API call of logger daemon is used to get extra information from terminated qemu process. For this purpose we need to wait until qemu process finishes its writing to log. We need to: 1. Read until EOF. 2. Don't stop reading on hangup. virtlogd will not receive EOF as both qemu and libvirtd keep logging pipe descriptor. Thus let's close it after qemu process startup is finished as it will not be used anymore. All following logging on behalf of qemu by libvirt is done either thru daemon API or by receiving new writing descriptor. Beware, qemuDomainLogContextFree is unref actually. --- src/logging/log_handler.c | 39 +++++++++++++++++++++++++++++++++++++-- src/qemu/qemu_domain.c | 4 ++++ src/qemu/qemu_domain.h | 1 + src/qemu/qemu_process.c | 2 ++ 4 files changed, 44 insertions(+), 2 deletions(-)

+static virLogHandlerLogFilePtr +virLogHandlerGetLogFileFromPath(virLogHandlerPtr handler, + const char* path) +{ + size_t i; + + for (i = 0; i < handler->nfiles; i++) { + if (STREQ(handler->files[i]->path, path)) + return handler->files[i]; + } + + return NULL; +}

@@ -167,11 +185,14 @@ virLogHandlerDomainLogFileEvent(int watch, goto error; } + if (len == 0) + goto error; + if (virRotatingFileWriterAppend(logfile->file, buf, len) != len) goto error; if (events & VIR_EVENT_HANDLE_HANGUP) - goto error; + goto reread;

virObjectUnlock(handler); return; @@ -179,6 +200,7 @@ virLogHandlerDomainLogFileEvent(int watch, error: handler->inhibitor(false, handler->opaque); virLogHandlerLogFileClose(handler, logfile); + virCondBroadcast(&handler->condition); virObjectUnlock(handler); } @@ -198,6 +220,9 @@ virLogHandlerNew(bool privileged, if (!(handler = virObjectLockableNew(virLogHandlerClass))) goto error; + if (virCondInit(&handler->condition) < 0) + goto error; + handler->privileged = privileged; handler->max_size = max_size; handler->max_backups = max_backups; @@ -357,6 +382,7 @@ virLogHandlerDispose(void *obj) virLogHandlerLogFileFree(handler->files[i]); } VIR_FREE(handler->files); + virCondDestroy(&handler->condition); } @@ -401,7 +427,8 @@ virLogHandlerDomainOpenLogFile(virLogHandlerPtr handler, pipefd[0] = -1; memcpy(file->domuuid, domuuid, VIR_UUID_BUFLEN); if (VIR_STRDUP(file->driver, driver) < 0 || - VIR_STRDUP(file->domname, domname) < 0) + VIR_STRDUP(file->domname, domname) < 0 || + VIR_STRDUP(file->path, path) < 0) goto error; if ((file->file = virRotatingFileWriterNew(path, @@ -496,6 +523,14 @@ virLogHandlerDomainReadLogFile(virLogHandlerPtr handler, virObjectLock(handler); + while (virLogHandlerGetLogFileFromPath(handler, path)) { + if (virCondWait(&handler->condition, &handler->parent.lock) < 0) { + virReportSystemError(errno, "%s", + _("failed to wait for EOF")); + goto error; + } + }