previously, when ISC_BUFFER_USEINLINE was defined, macros were
used to implement isc_buffer primitives (isc_buffer_init(),
isc_buffer_region(), etc). these macros were missing the DbC
assertions for those primitives, which made it possible for
coding errors to go undetected.
adding the assertions to the macros caused compiler warnings on
some platforms. therefore, this commit converts the ISC__BUFFER
macros to static inline functions instead, with assertions included,
and eliminates the non-inline implementation from buffer.c.
the --enable-buffer-useinline configure option has been removed.
The RAND_bytes() implementation differs between the OpenSSL versions and
uses the system entropy only for seeding its internal CSPRNG. The
uv_random() on the other hand uses the system provided CSPRNG.
Switch from RAND_bytes() to uv_random() to use system provided CSPRNG.
After the loopmgr work has been merged, we can now cleanup the TCP and
TLS protocols a little bit, because there are stronger guarantees that
the sockets will be kept on the respective loops/threads. We only need
asynchronous call for listening sockets (start, stop) and reading from
the TCP (because the isc_nm_read() might be called from read callback
again.
This commit does the following changes (they are intertwined together):
1. Cleanup most of the asynchronous events in the TCP code, and add
comments for the events that needs to be kept asynchronous.
2. Remove isc_nm_resumeread() from the netmgr API, and replace
isc_nm_resumeread() calls with existing isc_nm_read() calls.
3. Remove isc_nm_pauseread() from the netmgr API, and replace
isc_nm_pauseread() calls with a new isc_nm_read_stop() call.
4. Disable the isc_nm_cancelread() for the streaming protocols, only the
datagram-like protocols can use isc_nm_cancelread().
5. Add isc_nmhandle_close() that can be used to shutdown the socket
earlier than after the last detach. Formerly, the socket would be
closed only after all reading and sending would be finished and the
last reference would be detached. The new isc_nmhandle_close() can
be used to close the underlying socket earlier, so all the other
asynchronous calls would call their respective callbacks immediately.
Co-authored-by: Ondřej Surý <ondrej@isc.org>
Co-authored-by: Artem Boldariev <artem@isc.org>
In preparation for the on-loop timers, the isc_ratelimiter API was
converted to use the timer on main loop and start and stop the timer
asynchronously on the main loop.
As it sometimes happens that the object using isc_timer_t is destroyed
via detaching all the references with no guarantee that the last thread
will be matching thread, add a helper isc_timer_async_destroy() function
that stops the timer and runs the destroy function via isc_async_run()
on the matching thread.
When converting a string to lower case, the compiler is able to
autovectorize nicely, so a nice simple implementation is also very
fast, comparable to memcpy().
Comparisons are more difficult for the compiler, so we convert eight
bytes at a time using "SIMD within a register" tricks. Experiments
indicate it's best to stick to simple loops for shorter strings and
the remainder of long strings.
There were a number of places that had copies of various ASCII
tables (case conversion, hex and decimal conversion) that are intended
to be faster than the ctype.h macros, or avoid locale pollution.
Move them into libisc, and wrap the lookup tables with macros that
avoid the ctype.h gotchas.
Commit 3608abc8fa6a33046e1d34a0789cf7c9547f09ad inadvertently carried
over a mistake in logging pthread_cond_init() errors to the
ERRNO_CHECK() preprocessor macro: instead of passing the value returned
by a given pthread_*() function to strerror_r(), ERRNO_CHECK() passes
the errno variable to strerror_r(). This causes bogus error reports
because POSIX Threads API functions do not set the errno variable.
Fix by passing the value returned by a given pthread_*() function
instead of the errno variable to strerror_r(). Since this change makes
the name of the affected macro (ERRNO_CHECK()) confusing, rename the
latter to PTHREADS_RUNTIME_CHECK(). Also log the integer error value
returned by a given pthread_*() function verbatim to rule out any
further confusion in runtime error reporting.
Previously:
* applications were using isc_app as the base unit for running the
application and signal handling.
* networking was handled in the netmgr layer, which would start a
number of threads, each with a uv_loop event loop.
* task/event handling was done in the isc_task unit, which used
netmgr event loops to run the isc_event calls.
In this refactoring:
* the network manager now uses isc_loop instead of maintaining its
own worker threads and event loops.
* the taskmgr that manages isc_task instances now also uses isc_loopmgr,
and every isc_task runs on a specific isc_loop bound to the specific
thread.
* applications have been updated as necessary to use the new API.
* new ISC_LOOP_TEST macros have been added to enable unit tests to
run isc_loop event loops. unit tests have been updated to use this
where needed.
* isc_timer was rewritten using the uv_timer, and isc_timermgr_t was
completely removed; isc_timer objects are now directly created on the
isc_loop event loops.
* the isc_timer API has been simplified. the "inactive" timer type has
been removed; timers are now stopped by calling isc_timer_stop()
instead of resetting to inactive.
* isc_manager now creates a loop manager rather than a timer manager.
* modules and applications using isc_timer have been updated to use the
new API.
This commit introduces new APIs for applications and signal handling,
intended to replace isc_app for applications built on top of libisc.
* isc_app will be replaced with isc_loopmgr, which handles the
starting and stopping of applications. In isc_loopmgr, the main
thread is not blocked, but is part of the working thread set.
The loop manager will start a number of threads, each with a
uv_loop event loop running. Setup and teardown functions can be
assigned which will run when the loop starts and stops, and
jobs can be scheduled to run in the meantime. When
isc_loopmgr_shutdown() is run from any the loops, all loops
will shut down and the application can terminate.
* signal handling will now be handled with a separate isc_signal unit.
isc_loopmgr only handles SIGTERM and SIGINT for application
termination, but the application may install additional signal
handlers, such as SIGHUP as a signal to reload configuration.
* new job running primitives, isc_job and isc_async, have been added.
Both units schedule callbacks (specifying a callback function and
argument) on an event loop. The difference is that isc_job unit is
unlocked and not thread-safe, so it can be used to efficiently
run jobs in the same thread, while isc_async is thread-safe and
uses locking, so it can be used to pass jobs from one thread to
another.
* isc_tid will be used to track the thread ID in isc_loop worker
threads.
* unit tests have been added for the new APIs.
uv_barrier_init() errors are currently ignored. Use UV_RUNTIME_CHECK()
to catch them and to improve error reporting for any uv_barrier_init()
run-time failures (by augmenting error messages with file/line
information and the error string corresponding to the value returned).
Replace direct uses of implementation-specific rwlock functions in
lib/isc/include/isc/rwlock.h with preprocessor macros that use
ERRNO_CHECK(), in order to augment rwlock-related error messages with
file/line/caller information and the error string corresponding to
errno. Adjust the implementation-specific functions for pthreads-based
rwlocks so that they return any errors encountered to the caller instead
of aborting execution immediately using RUNTIME_CHECK().
To keep code modifications simple, make the non-pthreads-based
implementation-specific rwlock functions always return 0; these
functions continue to handle errors using less verbose run-time
assertions as they do not set errno anyway.
Replace all uses of RUNTIME_CHECK() in lib/isc/include/isc/condition.h
with ERRNO_CHECK(), in order to improve error reporting for any
condition-variable-related run-time failures (by augmenting error
messages with file/line/caller information and the error string
corresponding to errno).
Replace all uses of RUNTIME_CHECK() in lib/isc/include/isc/mutex.h with
ERRNO_CHECK(), in order to improve error reporting for any mutex-related
run-time failures (by augmenting error messages with file/line/caller
information and the error string corresponding to errno).
Some POSIX threads implementations (e.g. FreeBSD's libthr) allocate
memory on the heap when pthread_barrier_init() is called. Every call to
that function must be accompanied by a corresponding call to
pthread_barrier_destroy() or else the memory allocated for the barrier
will leak.
jemalloc can be used for detecting memory allocations which are not
released by a process when it exits. Unfortunately, since jemalloc is
also the system allocator on FreeBSD and a special (profiling-enabled)
build of jemalloc is required for memory leak detection, this method
cannot be used for detecting leaked memory allocated by libthr on a
stock FreeBSD installation.
However, libthr's behavior can be emulated on any platform by
implementing alternative versions of libisc functions for creating and
destroying barriers that allocate memory using malloc() and release it
using free(). This enables using jemalloc for detecting missing
pthread_barrier_destroy() calls on any platform on which it works
reliably.
When the newly introduced ISC_TRACK_PTHREADS_OBJECTS preprocessor macro
is set, allocate isc_barrier_t structures on the heap in
isc_barrier_init() and free them in isc_barrier_destroy(). Reuse
existing barrier macros (after renaming them appropriately) for other
operations.
Some POSIX threads implementations (e.g. FreeBSD's libthr) allocate
memory on the heap when pthread_rwlock_init() is called. Every call to
that function must be accompanied by a corresponding call to
pthread_rwlock_destroy() or else the memory allocated for the rwlock
will leak.
jemalloc can be used for detecting memory allocations which are not
released by a process when it exits. Unfortunately, since jemalloc is
also the system allocator on FreeBSD and a special (profiling-enabled)
build of jemalloc is required for memory leak detection, this method
cannot be used for detecting leaked memory allocated by libthr on a
stock FreeBSD installation.
However, libthr's behavior can be emulated on any platform by
implementing alternative versions of libisc functions for creating and
destroying rwlocks that allocate memory using malloc() and release it
using free(). This enables using jemalloc for detecting missing
pthread_rwlock_destroy() calls on any platform on which it works
reliably.
When the newly introduced ISC_TRACK_PTHREADS_OBJECTS preprocessor macro
is set (and --enable-pthread-rwlock is used), allocate isc_rwlock_t
structures on the heap in isc_rwlock_init() and free them in
isc_rwlock_destroy(). Reuse existing functions defined in
lib/isc/rwlock.c for other operations, but rename them first, so that
they contain triple underscores (to indicate that these functions are
implementation-specific, unlike their mutex and condition variable
counterparts, which always use the pthreads implementation). Define the
isc__rwlock_init() macro so that it is a logical counterpart of
isc__mutex_init() and isc__condition_init(); adjust isc___rwlock_init()
accordingly. Remove a redundant function prototype for
isc__rwlock_lock() and rename that (static) function to rwlock_lock() in
order to avoid having to use quadruple underscores.
Some POSIX threads implementations (e.g. FreeBSD's libthr) allocate
memory on the heap when pthread_cond_init() is called. Every call to
that function must be accompanied by a corresponding call to
pthread_cond_destroy() or else the memory allocated for the condition
variable will leak.
jemalloc can be used for detecting memory allocations which are not
released by a process when it exits. Unfortunately, since jemalloc is
also the system allocator on FreeBSD and a special (profiling-enabled)
build of jemalloc is required for memory leak detection, this method
cannot be used for detecting leaked memory allocated by libthr on a
stock FreeBSD installation.
However, libthr's behavior can be emulated on any platform by
implementing alternative versions of libisc functions for creating and
destroying condition variables that allocate memory using malloc() and
release it using free(). This enables using jemalloc for detecting
missing pthread_cond_destroy() calls on any platform on which it works
reliably.
When the newly introduced ISC_TRACK_PTHREADS_OBJECTS preprocessor macro
is set, allocate isc_condition_t structures on the heap in
isc_condition_init() and free them in isc_condition_destroy(). Reuse
existing condition variable macros (after renaming them appropriately)
for other operations.
Some POSIX threads implementations (e.g. FreeBSD's libthr) allocate
memory on the heap when pthread_mutex_init() is called. Every call to
that function must be accompanied by a corresponding call to
pthread_mutex_destroy() or else the memory allocated for the mutex will
leak.
jemalloc can be used for detecting memory allocations which are not
released by a process when it exits. Unfortunately, since jemalloc is
also the system allocator on FreeBSD and a special (profiling-enabled)
build of jemalloc is required for memory leak detection, this method
cannot be used for detecting leaked memory allocated by libthr on a
stock FreeBSD installation.
However, libthr's behavior can be emulated on any platform by
implementing alternative versions of libisc functions for creating and
destroying mutexes that allocate memory using malloc() and release it
using free(). This enables using jemalloc for detecting missing
pthread_mutex_destroy() calls on any platform on which it works
reliably.
Introduce a new ISC_TRACK_PTHREADS_OBJECTS preprocessor macro, which
causes isc_mutex_t structures to be allocated on the heap by
isc_mutex_init() and freed by isc_mutex_destroy(). Reuse existing mutex
macros (after renaming them appropriately) for other operations.
Instead of returning error values from isc_rwlock_*(), isc_mutex_*(),
and isc_condition_*() macros/functions and subsequently carrying out
runtime assertion checks on the return values in the calling code,
trigger assertion failures directly in those macros/functions whenever
any pthread function returns an error, as there is no point in
continuing execution in such a case anyway.
In a number of situations in pthreads-related code, a common sequence of
steps is taken: if the value returned by a library function is not 0,
pass errno to strerror_r(), log the string returned by the latter, and
immediately abort execution. Add an ERRNO_CHECK() preprocessor macro
which takes those exact steps and use it wherever (conveniently)
possible.
Notes:
1. The "log the return value of strerror_r() and abort" pattern is used
in a number of other places that this commit does not touch; only
"!= 0" checks followed by isc_error_fatal() calls with
non-customized error messages are replaced here.
2. This change temporarily breaks file name & line number reporting for
isc__mutex_init() errors, to prevent breaking the build. This issue
will be rectified in a subsequent change.
it's a style violation to have REQUIRE or INSIST contain code that
must run for the server to work. this was being done with some
atomic_compare_exchange calls. these have been cleaned up. uses
of atomic_compare_exchange in assertions have been replaced with
a new macro atomic_compare_exchange_enforced, which uses RUNTIME_CHECK
to ensure that the exchange was successful.
Previously, tasks could be created either unbound or bound to a specific
thread (worker loop). The unbound tasks would be assigned to a random
thread every time isc_task_send() was called. Because there's no logic
that would assign the task to the least busy worker, this just creates
unpredictability. Instead of random assignment, bind all the previously
unbound tasks to worker 0, which is guaranteed to exist.
This commit separates TLS context creation code from xfrin_start() as
it has become too large and hard to follow into a new
function (similarly how it is done in dighost.c)
The dead code has been removed from the cleanup section of the TLS
creation code:
* there is no way 'tlsctx' can equal 'found';
* there is no way 'sess_cache' can be non-NULL in the cleanup section.
Also, it fixes a bug in the older version of the code, where TLS
client session context fetched from the cache would not get passed to
isc_nm_tlsdnsconnect().
This commit extends TLS context cache with TLS client session cache so
that an associated session cache can be stored alongside the TLS
context within the context cache.
This commit adds an implementation of a client TLS session cache. TLS
client session cache is an object which allows efficient storing and
retrieval of previously saved TLS sessions so that they can be
resumed. This object is supposed to be a foundation for implementing
TLS session resumption - a standard technique to reduce the cost of
re-establishing a connection to the remote server endpoint.
OpenSSL does server-side TLS session caching transparently by
default. However, on the client-side, a TLS session to resume must be
manually specified when establishing the TLS connection. The TLS
client session cache is precisely the foundation for that.
Clang added support for the gcc-style fallthrough
attribute (i.e. __attribute__((fallthrough))) in version 10. However,
__has_attribute(fallthrough) will return 1 in C mode in older versions,
even though they only support the C++11 fallthrough attribute. At best,
the unsupported attribute is simply ignored; at worst, it causes errors.
The C2x fallthrough attribute has the advantages of being supported in
the broadest range of clang versions (added in version 9) and being easy
to check for support. Use C2x [[fallthrough]] attribute if possible, and
fall back to not using an attribute for clang versions that don't have
it.
Courtesy of Joshua Root
Since the fctx hash table is now self-resizing, and resolver tasks are
selected to match the thread that created the fetch context, there
shouldn't be any significant advantage to having multiple tasks per CPU;
a single task per thread should be sufficient.
Additionally, the fetch context is always pinned to the calling netmgr
thread to minimize the contention just to coalesced fetches - if two
threads starts the same fetch, it will be pinned to the first one to get
the bucket.
After removing the isc_task_onshutdown(), the isc_task_shutdown() and
isc_task_destroy() became obsolete.
Remove calls to isc_task_shutdown() and replace the calls to
isc_task_destroy() with isc_task_detach().
Simplify the internal logic to destroy the task when the last reference
is removed.
The isc_task_onshutdown() was used to post event that should be run when
the task is being shutdown. This could happen explicitly in the
isc_test_shutdown() call or implicitly when we detach the last reference
to the task and there are no more events posted on the task.
This whole task onshutdown mechanism just makes things more complicated,
and it's easier to post the "shutdown" events when we are shutting down
explicitly and the existing code already always knows when it should
shutdown the task that's being used to execute the onshutdown events.
Replace the isc_task_onshutdown() calls with explicit calls to execute
the shutdown tasks.
As we are going to use libuv outside of the netmgr, we need the shims to
be readily available for the rest of the codebase.
Move the "netmgr/uv-compat.h" to <isc/uv.h> and netmgr/uv-compat.c to
uv.c, and as a rule of thumb, the users of libuv should include
<isc/uv.h> instead of <uv.h> directly.
Additionally, merge netmgr/uverr2result.c into uv.c and rename the
single function from isc__nm_uverr2result() to isc_uverr2result().
It used to require two 32-bit integer divisions to get a random number
less than some limit. Now we use Daniel Lemire's "nearly-divisionless"
algorithm for unbiased bounded random numbers, which requires one
64-bit integer multiply in the usual case, and one 32-bit integer
division in rare slow cases. Even the slow cases are faster than
before; there are also fewer branches.
I think this algorithm is exceptionally beautiful. It also has more
clever tricks than lines of code, so I have done my best to explain
how it works.
When TASKMGR_TRACE=1 is defined, the task and event objects have
detailed tracing information about function, file, line, and
backtrace (to the extent tracked by gcc) where it was created.
At exit, when there are unfinished tasks, they will be printed along
with the detailed information.
The only place where isc_task_sendto() was used was in dns_resolver
unit, where the "sendto" part was actually no-op, because dns_resolver
uses bound tasks. Remove the isc_task_sendto() and
isc_task_sendtoanddetach() functions in favor of using bound tasks
create with isc_task_create_bound().
Additionally, cache the number of running netmgr threads (nworkers)
locally to reduce the number of function calls.
For some applications, it's useful to not listen on full battery of
threads. Add workers argument to all isc_nm_listen*() functions and
convenience ISC_NM_LISTEN_ONE and ISC_NM_LISTEN_ALL macros.
This commit adds isc_nmsocket_set_tlsctx() - an asynchronous function
that replaces the TLS context within a given TLS-enabled listener
socket object. It is based on the newly added reference counting
functionality.
The intention of adding this function is to add functionality to
replace a TLS context without recreating the whole socket object,
including the underlying TCP listener socket, as a BIND process might
not have enough permissions to re-create it fully on reconfiguration.
The implementation is done on top of the reference counting
functionality found in OpenSSL/LibreSSL, which allows for avoiding
wrapping the object.
Adding this function allows using reference counting for TLS contexts
in BIND 9's codebase.
Previously, HAVE_SO_REUSEPORT_LB has been defined only in the private
netmgr-int.h header file, making the configuration of load balanced
sockets inoperable.
Move the missing HAVE_SO_REUSEPORT_LB define the isc/netmgr.h and add
missing isc_nm_getloadbalancesockets() implementation.
Previously, the option to enable kernel load balancing of the sockets
was always enabled when supported by the operating system (SO_REUSEPORT
on Linux and SO_REUSEPORT_LB on FreeBSD).
It was reported that in scenarios where the networking threads are also
responsible for processing long-running tasks (like RPZ processing, CATZ
processing or large zone transfers), this could lead to intermitten
brownouts for some clients, because the thread assigned by the operating
system might be busy. In such scenarious, the overall performance would
be better served by threads competing over the sockets because the idle
threads can pick up the incoming traffic.
Add new configuration option (`load-balance-sockets`) to allow enabling
or disabling the load balancing of the sockets.
Previously, the RPZ updates ran quantized on the main nm_worker loops.
As the quantum was set to 1024, this might lead to service
interruptions when large RPZ update was processed.
Change the RPZ update process to run as the offloaded work. The update
and cleanup loops were refactored to do as little locking of the
maintenance lock as possible for the shortest periods of time and the db
iterator is being paused for every iteration, so we don't hold the rbtdb
tree lock for prolonged periods of time.
The reference counting and isc_timer_attach()/isc_timer_detach()
semantic are actually misleading because it cannot be used under normal
conditions. The usual conditions under which is timer used uses the
object where timer is used as argument to the "timer" itself. This
means that when the caller is using `isc_timer_detach()` it needs the
timer to stop and the isc_timer_detach() does that only if this would be
the last reference. Unfortunately, this also means that if the timer is
attached elsewhere and the timer is fired it will most likely be
use-after-free, because the object used in the timer no longer exists.
Remove the reference counting from the isc_timer unit, remove
isc_timer_attach() function and rename isc_timer_detach() to
isc_timer_destroy() to better reflect how the API needs to be used.
The only caveat is that the already executed event must be destroyed
before the isc_timer_destroy() is called because the timer is no longet
attached to .ev_destroy_arg.
