search for: _thread_model

...| 115 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ > src/plugins.c | 77 +++++------------------------------- > 5 files changed, 142 insertions(+), 79 deletions(-) > > +++ b/src/locks.c > +void > +lock_connection (void) > +{ > + int thread_model = plugin_thread_model (); > + > + if (thread_model <= NBDKIT_THREAD_MODEL_SERIALIZE_CONNECTIONS) { > +++ b/src/plugins.c > +int > +plugin_thread_model (void) > +{ > + assert (dl); > + > + return plugin._thread_model; > +} The new code asserts dl prior to locking the connection; &g...

...11a810..74bb8e4 100644 --- a/src/connections.c +++ b/src/connections.c @@ -211,7 +211,7 @@ _handle_single_connection (int sockin, int sockout) int nworkers = threads ? threads : DEFAULT_PARALLEL_REQUESTS; pthread_t *workers = NULL; - if (!plugin_is_parallel() || nworkers == 1) + if (plugin_thread_model () < NBDKIT_THREAD_MODEL_PARALLEL || nworkers == 1) nworkers = 0; conn = new_connection (sockin, sockout, nworkers); if (!conn) @@ -287,9 +287,9 @@ handle_single_connection (int sockin, int sockout) { int r; - plugin_lock_connection (); + lock_connection (); r = _handle_sin...

...11a810..74bb8e4 100644 --- a/src/connections.c +++ b/src/connections.c @@ -211,7 +211,7 @@ _handle_single_connection (int sockin, int sockout) int nworkers = threads ? threads : DEFAULT_PARALLEL_REQUESTS; pthread_t *workers = NULL; - if (!plugin_is_parallel() || nworkers == 1) + if (plugin_thread_model () < NBDKIT_THREAD_MODEL_PARALLEL || nworkers == 1) nworkers = 0; conn = new_connection (sockin, sockout, nworkers); if (!conn) @@ -287,9 +287,9 @@ handle_single_connection (int sockin, int sockout) { int r; - plugin_lock_connection (); + lock_connection (); r = _handle_sin...

...d (); @@ -163,6 +169,8 @@ plugin_cleanup (void) dl = NULL; free (filename); filename = NULL; + + pthread_rwlock_unlock (&unload_prevention_lock); } } @@ -299,8 +307,6 @@ plugin_config_complete (void) void plugin_lock_connection (void) { - assert (dl); - if (plugin._thread_model <= NBDKIT_THREAD_MODEL_SERIALIZE_CONNECTIONS) { debug ("%s: acquire connection lock", filename); pthread_mutex_lock (&connection_lock); @@ -310,8 +316,6 @@ plugin_lock_connection (void) void plugin_unlock_connection (void) { - assert (dl); - if (plugin._thread_mode...

Somewhat invasive but mostly mechanical change to how plugins are called. This patch is in preparation for adding a second backend subtype for filters. Rich.

v1 -> v2: - Fixed everything mentioned in the review. Rich.

...lugin.pod b/plugins/rust/nbdkit-rust-plugin.pod index 930829cc..61c2e0ba 100644 --- a/plugins/rust/nbdkit-rust-plugin.pod +++ b/plugins/rust/nbdkit-rust-plugin.pod @@ -37,14 +37,19 @@ compatible with the C struct used by C plugins. use nbdkit::ThreadModel::*; #[no_mangle] + extern fn myplugin_thread_model () -> ThreadModel { + Serialize_AllRequests + } + + //... more functions + pub extern fn plugin_init () -> *const Plugin { // Plugin name. let name = "myplugin\0" as *const str as *const [c_char] as *const c_char; - // Create a mutable plugin, setting the...

...gin.pod > index 930829cc..61c2e0ba 100644 > --- a/plugins/rust/nbdkit-rust-plugin.pod > +++ b/plugins/rust/nbdkit-rust-plugin.pod > @@ -37,14 +37,19 @@ compatible with the C struct used by C plugins. > use nbdkit::ThreadModel::*; > > #[no_mangle] > + extern fn myplugin_thread_model () -> ThreadModel { > + Serialize_AllRequests > + } > + > + //... more functions > + > pub extern fn plugin_init () -> *const Plugin { > // Plugin name. > let name = "myplugin\0" > as *const str as *const [c_char] as *const c_char;...

Similar to what I just did for OCaml (this IS an API break, requiring recompilation of any existing Rust plugin), and done because I want to add fast_zero support to both languages as part of my upcoming fast zero series. Figuring out how to get extents working was hard enough that I punted that, still. Eric Blake (2): rust: Implement can_cache rust: Add support for dynamic .thread_model

This fixes the race conditions for me, using the test described here: https://www.redhat.com/archives/libguestfs/2017-September/msg00226.html Rich.

The concern is a client is blocked while processing a request. The nbdkit server design requires a thread per request being processed regardless of the number of connections or clients. We want to run 1000's of requests in parallel without needing a thread at nbdkit layer per request in flight. Our plugin layer is built around boost asio and a few threads in a worker pool running an io

...;THREAD_MODEL>, the C<.thread_model> if present, and any restrictions +requested by filters. The possible settings for C<THREAD_MODEL> are defined below. @@ -935,7 +959,8 @@ parallel. However only one request will happen per handle at a time =item C<#define THREAD_MODEL NBDKIT_THREAD_MODEL_PARALLEL> Multiple handles can be open and multiple data requests can happen in -parallel (even on the same handle). +parallel (even on the same handle). The server may reorder replies, +answering a later request before an earlier one. All the libraries you use must be thread-safe and reent...

...src/connections.c b/src/connections.c index 74bb8e4..921a5b2 100644 --- a/src/connections.c +++ b/src/connections.c @@ -211,16 +211,17 @@ _handle_single_connection (int sockin, int sockout) int nworkers = threads ? threads : DEFAULT_PARALLEL_REQUESTS; pthread_t *workers = NULL; - if (plugin_thread_model () < NBDKIT_THREAD_MODEL_PARALLEL || nworkers == 1) + if (backend->thread_model (backend) < NBDKIT_THREAD_MODEL_PARALLEL || + nworkers == 1) nworkers = 0; conn = new_connection (sockin, sockout, nworkers); if (!conn) goto done; - if (plugin_open (conn, readonly) ==...

...s(+), 68 deletions(-) diff --git a/docs/nbdkit-filter.pod b/docs/nbdkit-filter.pod index 4033789..86894f1 100644 --- a/docs/nbdkit-filter.pod +++ b/docs/nbdkit-filter.pod @@ -6,8 +6,6 @@ nbdkit-filter - how to write nbdkit filters #include <nbdkit-filter.h> - #define THREAD_MODEL NBDKIT_THREAD_MODEL_PARALLEL - static int myfilter_config (nbdkit_next_config *next, void *nxdata, const char *key, const char *value) @@ -107,24 +105,6 @@ should not expect to distribute filters separately from nbdkit. All filters should start by including this header file. -=head1 C<#de...

...src/connections.c b/src/connections.c index 74bb8e4..921a5b2 100644 --- a/src/connections.c +++ b/src/connections.c @@ -211,16 +211,17 @@ _handle_single_connection (int sockin, int sockout) int nworkers = threads ? threads : DEFAULT_PARALLEL_REQUESTS; pthread_t *workers = NULL; - if (plugin_thread_model () < NBDKIT_THREAD_MODEL_PARALLEL || nworkers == 1) + if (backend->thread_model (backend) < NBDKIT_THREAD_MODEL_PARALLEL || + nworkers == 1) nworkers = 0; conn = new_connection (sockin, sockout, nworkers); if (!conn) goto done; - if (plugin_open (conn, readonly) ==...

...src/connections.c b/src/connections.c index 74bb8e4..921a5b2 100644 --- a/src/connections.c +++ b/src/connections.c @@ -211,16 +211,17 @@ _handle_single_connection (int sockin, int sockout) int nworkers = threads ? threads : DEFAULT_PARALLEL_REQUESTS; pthread_t *workers = NULL; - if (plugin_thread_model () < NBDKIT_THREAD_MODEL_PARALLEL || nworkers == 1) + if (backend->thread_model (backend) < NBDKIT_THREAD_MODEL_PARALLEL || + nworkers == 1) nworkers = 0; conn = new_connection (sockin, sockout, nworkers); if (!conn) goto done; - if (plugin_open (conn, readonly) ==...

...ins/ocaml/ocaml.c b/plugins/ocaml/ocaml.c index f664a7fb..01f4448f 100644 --- a/plugins/ocaml/ocaml.c +++ b/plugins/ocaml/ocaml.c @@ -72,6 +72,7 @@ static void remove_roots (void); static struct nbdkit_plugin plugin = { ._struct_size = sizeof (plugin), ._api_version = NBDKIT_API_VERSION, + ._thread_model = NBDKIT_THREAD_MODEL_PARALLEL, /* The following field is used as a canary to detect whether the * OCaml code started up and called us back successfully. If it's @@ -131,6 +132,8 @@ static value extents_fn; static value can_cache_fn; static value cache_fn; +static value thread_model...

There are few more things that could be cleaned up related to the coding style and other things, like explicitly specifying the abi style after "extern" (i.e. `extern "C" fn` instead of `extern fn`), but since those are configurable in rustfmt config, I'm not sure whether the config needs to be added or complying with the defaults should be the priority. But this was just

...ted in one thread to a child process +created in another (either by always using atomic C<FD_CLOEXEC>, or by +closing unexpected fds between fork and exec). On platforms where +this is 0 and nbdkit cannot atomically set C<FD_CLOEXEC>, the thread +model will be restricted to +C<NBDKIT_THREAD_MODEL_SERIALIZE_ALL_REQUESTS> to avoid leaking file +descriptors. + =back =head1 THREADS @@ -942,8 +954,9 @@ C<NBDKIT_REGISTER_PLUGIN>). Additionally, a plugin may implement the C<.thread_model> callback, called right after C<.config_complete> to make a runtime decision on whic...

...(void) \ + { \ + (plugin)._struct_size = sizeof (plugin); \ + (plugin)._api_version = NBDKIT_API_VERSION; \ + (plugin)._thread_model = THREAD_MODEL; \ + return &(plugin); \ + } \ + NBDKIT_CXX_LANG_C __declspec(dllexport) \ + void...