Merge "add base::WaitForPropertyCreation"
diff --git a/base/include/android-base/properties.h b/base/include/android-base/properties.h
index e2324b7..4de5e57 100644
--- a/base/include/android-base/properties.h
+++ b/base/include/android-base/properties.h
@@ -66,6 +66,12 @@
const std::string& expected_value,
std::chrono::milliseconds relative_timeout);
+// Waits for the system property `key` to be created.
+// Times out after `relative_timeout`.
+// Returns true on success, false on timeout.
+bool WaitForPropertyCreation(const std::string& key,
+ std::chrono::milliseconds relative_timeout);
+
} // namespace base
} // namespace android
diff --git a/base/properties.cpp b/base/properties.cpp
index acd6c0f..32c0128 100644
--- a/base/properties.cpp
+++ b/base/properties.cpp
@@ -108,8 +108,10 @@
ts.tv_nsec = ns.count();
}
+using AbsTime = std::chrono::time_point<std::chrono::steady_clock>;
+
static void UpdateTimeSpec(timespec& ts,
- const std::chrono::time_point<std::chrono::steady_clock>& timeout) {
+ const AbsTime& timeout) {
auto now = std::chrono::steady_clock::now();
auto remaining_timeout = std::chrono::duration_cast<std::chrono::nanoseconds>(timeout - now);
if (remaining_timeout < 0ns) {
@@ -119,13 +121,16 @@
}
}
-bool WaitForProperty(const std::string& key,
- const std::string& expected_value,
- std::chrono::milliseconds relative_timeout) {
+// Waits for the system property `key` to be created.
+// Times out after `relative_timeout`.
+// Sets absolute_timeout which represents absolute time for the timeout.
+// Returns nullptr on timeout.
+static const prop_info* WaitForPropertyCreation(const std::string& key,
+ const std::chrono::milliseconds& relative_timeout,
+ AbsTime& absolute_timeout) {
// TODO: boot_clock?
auto now = std::chrono::steady_clock::now();
- std::chrono::time_point<std::chrono::steady_clock> absolute_timeout = now + relative_timeout;
- timespec ts;
+ absolute_timeout = now + relative_timeout;
// Find the property's prop_info*.
const prop_info* pi;
@@ -133,14 +138,25 @@
while ((pi = __system_property_find(key.c_str())) == nullptr) {
// The property doesn't even exist yet.
// Wait for a global change and then look again.
+ timespec ts;
UpdateTimeSpec(ts, absolute_timeout);
- if (!__system_property_wait(nullptr, global_serial, &global_serial, &ts)) return false;
+ if (!__system_property_wait(nullptr, global_serial, &global_serial, &ts)) return nullptr;
}
+ return pi;
+}
+
+bool WaitForProperty(const std::string& key,
+ const std::string& expected_value,
+ std::chrono::milliseconds relative_timeout) {
+ AbsTime absolute_timeout;
+ const prop_info* pi = WaitForPropertyCreation(key, relative_timeout, absolute_timeout);
+ if (pi == nullptr) return false;
WaitForPropertyData data;
data.expected_value = &expected_value;
data.done = false;
while (true) {
+ timespec ts;
// Check whether the property has the value we're looking for?
__system_property_read_callback(pi, WaitForPropertyCallback, &data);
if (data.done) return true;
@@ -152,5 +168,11 @@
}
}
+bool WaitForPropertyCreation(const std::string& key,
+ std::chrono::milliseconds relative_timeout) {
+ AbsTime absolute_timeout;
+ return (WaitForPropertyCreation(key, relative_timeout, absolute_timeout) != nullptr);
+}
+
} // namespace base
} // namespace android
diff --git a/base/properties_test.cpp b/base/properties_test.cpp
index c68c2f8..1bbe482 100644
--- a/base/properties_test.cpp
+++ b/base/properties_test.cpp
@@ -150,3 +150,25 @@
// Upper bounds on timing are inherently flaky, but let's try...
ASSERT_LT(std::chrono::duration_cast<std::chrono::milliseconds>(t1 - t0), 600ms);
}
+
+TEST(properties, WaitForPropertyCreation) {
+ std::thread thread([&]() {
+ std::this_thread::sleep_for(100ms);
+ android::base::SetProperty("debug.libbase.WaitForPropertyCreation_test", "a");
+ });
+
+ ASSERT_TRUE(android::base::WaitForPropertyCreation(
+ "debug.libbase.WaitForPropertyCreation_test", 1s));
+ thread.join();
+}
+
+TEST(properties, WaitForPropertyCreation_timeout) {
+ auto t0 = std::chrono::steady_clock::now();
+ ASSERT_FALSE(android::base::WaitForPropertyCreation(
+ "debug.libbase.WaitForPropertyCreation_timeout_test", 200ms));
+ auto t1 = std::chrono::steady_clock::now();
+
+ ASSERT_GE(std::chrono::duration_cast<std::chrono::milliseconds>(t1 - t0), 200ms);
+ // Upper bounds on timing are inherently flaky, but let's try...
+ ASSERT_LT(std::chrono::duration_cast<std::chrono::milliseconds>(t1 - t0), 600ms);
+}