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authorJosé Bollo <jose.bollo@iot.bzh>2019-01-05 21:22:39 +0100
committerJan-Simon Moeller <jsmoeller@linuxfoundation.org>2019-02-05 17:45:54 +0000
commit42dbcc0d19bc5571c3e80588139a069128551900 (patch)
tree4311fa823f3159d0af84563ff3358df98b6935f6
parentbab3af6af16591d4d95275fac3c6d920ab9f4b41 (diff)
Avoid concurrency with the thread managing the event loop by using condition variables. Also, improve safety of link to event loop: instead of using the default one that depends on the current thread and that might be shared with other items, use an explicit new one running in a dedicated thread. Change-Id: I3d6fd2fd52a97dae42228657a09b8b0a15b96edf Signed-off-by: José Bollo <jose.bollo@iot.bzh> (cherry picked from commit e88fb8522d335b9a7fb723ae5656dc9b2e7850c7)
-rw-r--r--src/libwindowmanager.cpp83
1 files changed, 37 insertions, 46 deletions
diff --git a/src/libwindowmanager.cpp b/src/libwindowmanager.cpp
index 515fea1..22bec4f 100644
--- a/src/libwindowmanager.cpp
+++ b/src/libwindowmanager.cpp
@@ -206,7 +206,7 @@ int LibWindowmanager::Impl::init(int port, char const *token) {
}
/* get the default event loop */
- rc = sd_event_default(&this->loop);
+ rc = sd_event_new(&this->loop);
if (rc < 0) {
HMI_ERROR("libwm", "Connection to default event loop failed: %s",
strerror(-rc));
@@ -621,6 +621,41 @@ std::pair<bool, LibWindowmanager::EventType> make_event_type(char const *et) {
}
} // namespace
+#include <condition_variable>
+#include <mutex>
+class callsync {
+private:
+ const std::function<void(bool, json_object *)> &onReply_;
+ std::condition_variable cond_;
+ std::mutex mutex_;
+ bool ok_;
+private:
+ static void on_reply(void *closure, afb_wsj1_msg *msg) {
+ callsync *call = reinterpret_cast<callsync*>(closure);
+ call->onReply_(call->ok_ = afb_wsj1_msg_is_reply_ok(msg), afb_wsj1_msg_object_j(msg));
+ call->cond_.notify_one();
+ afb_wsj1_msg_unref(msg);
+ }
+public:
+ callsync(
+ struct afb_wsj1 *wsj1,
+ const char *api,
+ const char *verb,
+ json_object *args,
+ const std::function<void(bool, json_object *)> &onReply
+ )
+ : onReply_(onReply), cond_(), mutex_(), ok_(false) {
+ std::unique_lock<std::mutex> ulock(mutex_);
+ int rc = afb_wsj1_call_j(wsj1, api, verb, args, on_reply, this);
+ if (rc < 0)
+ onReply(false, nullptr);
+ else
+ cond_.wait(ulock);
+ }
+ operator bool() const { return ok_; }
+ operator int() const { return int(ok_) - 1; }
+};
+
/// object will be json_object_put
int LibWindowmanager::Impl::api_call(
const char *verb, json_object *object,
@@ -631,51 +666,7 @@ int LibWindowmanager::Impl::api_call(
if ((0 == strcmp("RequestSurface", verb)) ||
(0 == strcmp("GetDisplayInfo", verb)) ||
(0 == strcmp("GetAreaInfo", verb))) {
- // We need to wrap the actual onReply call once in order to
- // *look* like a normal functions pointer (std::functions<>
- // with captures cannot convert to function pointers).
- // Alternatively we could setup a local struct and use it as
- // closure, but I think it is cleaner this way.
- int call_rc = 0;
- std::atomic<bool> returned{};
- returned.store(false, std::memory_order_relaxed);
- std::function<void(bool, json_object *)> wrappedOnReply =
- [&returned, &call_rc, &onReply](bool ok, json_object *j) {
- TRACEN(wrappedOnReply);
- call_rc = ok ? 0 : -EINVAL;
- // We know it failed, but there may be an explanation in the
- // json object.
- {
- TRACEN(onReply);
- onReply(ok, j);
- }
- returned.store(true, std::memory_order_release);
- };
-
- // make the actual call, use wrappedOnReply as closure
- rc = afb_wsj1_call_j(
- this->wsj1, wmAPI, verb, object,
- [](void *closure, afb_wsj1_msg *msg) {
- TRACEN(callClosure);
- auto *onReply =
- reinterpret_cast<std::function<void(bool, json_object *)> *>(
- closure);
- (*onReply)(!(afb_wsj1_msg_is_reply_ok(msg) == 0),
- afb_wsj1_msg_object_j(msg));
- },
- &wrappedOnReply);
-
- if (0 == rc) {
- // We need to wait until "returned" got set, this is necessary
- // if events get triggered by the call (and would be dispatched before
- // the actual call-reply).
- while (!returned.load(std::memory_order_consume)) {
- sd_event_run(loop, 16);
- }
-
- // return the actual API call result
- rc = call_rc;
- }
+ rc = callsync(this->wsj1, wmAPI, verb, object, onReply);
}
else {
rc = afb_wsj1_call_j(this->wsj1, wmAPI, verb, object, _on_reply_static, this);