Buffer for application prefork request allocated from temp conf mem_pool.
If error response from main process received before buffer completion handler,
temp conf mem_pool destroyed and router may crash in completion handler.
Assertion "src/nxt_buf.c:208 assertion failed: data == b->parent" triggered
when NXT_DEBUG_ALLOC enabled in configure.
This patch disables completion handler and memory allocated for buffer
released with memory pool.
Previously, an error during the prefork phase triggered assert:
src/nxt_port.c:27 assertion failed: port->pair[0] == -1
and resulted in exiting of the main process.
This could be easily reproduced by pushing a configuration with "rootfs",
when daemon is running without required permissions.
The default libunit behavior relies on blocking the recv() call for port file
descriptors, which an application may override if needed. For external
applications, port file descriptors were toggled to blocking mode before the
exec() call. If the exec() call failed, descriptor remained blocked, so the
process hanged while trying to read from it.
This patch moves file descriptor mode switch inside libunit.
Generic process-to-process shared memory exchange is no more required. Here,
it is transformed into a router-to-application pattern. The outgoing shared
memory segments collection is now the property of the application structure.
The applications connect to the router only, and the process only needs to group
the ports.
This is the port shared between all application processes which use it to pass
requests for processing. Using it significantly simplifies the request
processing code in the router. The drawback is 2 more file descriptors per each
configured application and more complex libunit message wait/read code.
The application process needs to request the shared memory segment from the
router instead of the latter pushing the segment before sending a request to
the application. This is required to simplify the communication between the
router and the application and to prepare the router for using the application
shared port and then the queue.
The application process needs to request the port from the router instead of the
latter pushing the port before sending a request to the application. This is
required to simplify the communication between the router and the application
and to prepare the router to use the application shared port and then the queue.
The goal is to minimize the number of (pid, id) to port hash lookups which
require a library mutex lock. The response port is found once per request,
while the read port is initialized at startup.
- Changed the port management callbacks to notifications, which e. g. avoids
the need to call the libunit function
- Added context and library instance reference counts for a safer resource
release
- Added the router main port initialization
If there are no listen sockets, the router configuration usage counter
remains 0 and never decreases. The only moment to release a configuration is
right after a configuration update.
According to libuv documentation, uv_poll_t memory should be released
in a callback function passed to uv_close(). Otherwise, the Node.js application
process may crash at exit.
A connection object is allocated in advance for each listen event object to be
used for the established connection. This connection needs to be freed when the
listen event is destroyed.
The invocation parameters should be logged as well, notably the path of the file
that is failed to be created.
Also, log level changed to ALERT as it's quite critical error.
Earlier, if nxt_mp_create() failed to allocate memory while accepting a new
connection, the resulting NULL was subsequently passed to nxt_mp_destroy(),
crashing the process.
More, if nxt_mp_create() was successful but nxt_sockaddr_cache_alloc() failed,
the connection object wasn't destroyed properly, leaving the connection counter
in an inconsistent state. Repeated, this condition lowered the connection
capacity of the process and could eventually prevent it from accepting
connections altogether.
Since the introduction of rootfs feature, some language modules
can't be configured multiple times.
Now the configure generates a separate nxt_<module>_mounts.h for
each module compiled.
There is no restrictions on configration size and using segmented shared memory
only doubles memory usage because to parse configration on router side,
it needs to be 'plain' e. g. located in single continous memory buffer.
Currently, the router exits without waiting for the worker threads to stop.
There is a short gap between the runtime memory pool's free and the exit, during
which a worker thread may try to access a runtime structure. In turn, this may
cause a crash. For now, it is better to keep this memory allocated.
Correct value for non-initialized file descriptor is -1, because most of the
checks in libunit compares file descriptor with -1 before performing an
action. Using 0 as default value, may cause to close file descriptor #0, this
may affect application logic.
It is not required to list this patch in changelog because impact is not seen
by end users.
The nxt_assert macro uses nxt_thread_context, which caused the following linker
error when using it in the library:
ld: illegal thread local variable reference to regular symbol
_nxt_thread_context for architecture x86_64
Previously, the log message callback used a generic log function, that relied on the process time cache.
Since there were no time update calls in the application processes, all log lines were printed with the
same time, usually correlated with the process start.
Now, a non-cached logging function from libunit is used.
This makes log format used in libunit consistent with the daemon, where milliseconds are printed only in the
debug log level.
Currently a compile time switch is used, since there's no support for runtime changing of a log level for now.
But in the future this should be a runtime condition, similar to nxt_log_time_handler().
The lifespan of a listening socket is longer than both router
configuration's and temporary router configuration's lifespan,
so the sockets should be stored in persistent queues. Safety
is ensured by the fact that the router processes only one new
configuration at any time.
