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MXS-1775 Ensure MonitorInstance::start() returns correct value

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Since we need to call mysql_thread_init(), which can fail, in
the monitor thread, we need to wait for the outcome of that
before we can return from start().
This commit is contained in:
Johan Wikman 2018-05-17 14:21:34 +03:00
parent 650a739c92
commit 9d526332d8
2 changed files with 28 additions and 14 deletions
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14
include/maxscale/monitor.hh
View File

@ -14,6 +14,7 @@
#include <maxscale/cppdefs.hh>
#include <maxscale/monitor.h>
#include <maxscale/semaphore.hh>
#include <maxscale/thread.h>
namespace maxscale
@ -44,12 +45,13 @@ protected:
MXS_MONITORED_SERVER* m_master; /**< Master server */
private:
int32_t m_status; /**< The current status of the monitor. */
THREAD m_thread; /**< The thread handle of the monitoring thread. */
int32_t m_shutdown; /**< Non-zero if the monitor should shut down. */
bool m_checked; /**< Whether server access has been checked. */
std::string m_script; /**< Launchable script. */
uint64_t m_events; /**< Enabled monitor events. */
int32_t m_status; /**< The current status of the monitor. */
THREAD m_thread; /**< The thread handle of the monitoring thread. */
int32_t m_shutdown; /**< Non-zero if the monitor should shut down. */
bool m_checked; /**< Whether server access has been checked. */
std::string m_script; /**< Launchable script. */
uint64_t m_events; /**< Enabled monitor events. */
Semaphore m_semaphore; /**< Semaphore for synchronizing with monitor thread. */
void main();

28
server/core/monitor.cc
View File

@ -2542,6 +2542,7 @@ bool MonitorInstance::start(const MXS_CONFIG_PARAMETER* pParams)
ss_dassert(!m_shutdown);
ss_dassert(!m_thread);
ss_dassert(m_status == MXS_MONITOR_STOPPED);
if (!m_checked)
{
@ -2569,7 +2570,19 @@ bool MonitorInstance::start(const MXS_CONFIG_PARAMETER* pParams)
}
else
{
started = true;
// Ok, so the thread started. Let's wait until we can be certain the
// state has been updated.
m_semaphore.wait();
started = (atomic_load_int32(&m_status) == MXS_MONITOR_RUNNING);
if (!started)
{
// Ok, so the initialization failed and the thread will exit.
// We need to wait on it so that the thread resources will not leak.
thread_wait(m_thread);
m_thread = 0;
}
}
}
@ -2587,8 +2600,6 @@ void MonitorInstance::configure(const MXS_CONFIG_PARAMETER* pParams)
void MonitorInstance::main()
{
atomic_store_int32(&m_status, MXS_MONITOR_RUNNING);
load_server_journal(m_monitor, &m_master);
while (!m_shutdown)
@ -2622,8 +2633,6 @@ void MonitorInstance::main()
ms += MXS_MON_BASE_INTERVAL_MS;
}
}
atomic_store_int32(&m_status, MXS_MONITOR_STOPPED);
}
//static
@ -2633,17 +2642,20 @@ void MonitorInstance::main(void* pArg)
if (mysql_thread_init() == 0)
{
atomic_store_int32(&pThis->m_status, MXS_MONITOR_RUNNING);
pThis->m_semaphore.post();
pThis->main();
atomic_store_int32(&pThis->m_status, MXS_MONITOR_STOPPED);
mysql_thread_end();
}
else
{
MXS_ERROR("mysql_thread_init() failed for %s. The monitor cannot start.",
pThis->m_monitor->name);
// TODO: MaxScale now thinks the monitor is running, as startMonitor()
// TODO: already returned true.
pThis->m_semaphore.post();
}
}