Implement android::base::WaitForProperty.
Also adapt libcutils to the bionic change that was necessary for this.
Bug: http://b/35201172
Test: ran tests
Change-Id: I72a98b70b03d23e958b46778b505fbd5c86c32ae
diff --git a/base/properties.cpp b/base/properties.cpp
index 37daf9a..0f0f638 100644
--- a/base/properties.cpp
+++ b/base/properties.cpp
@@ -14,9 +14,12 @@
* limitations under the License.
*/
+#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
+
#include "android-base/properties.h"
#include <sys/system_properties.h>
+#include <sys/_system_properties.h>
#include <string>
@@ -78,5 +81,43 @@
return (__system_property_set(key.c_str(), value.c_str()) == 0);
}
+struct WaitForPropertyData {
+ bool done;
+ const std::string* expected_value;
+ unsigned last_read_serial;
+};
+
+static void WaitForPropertyCallback(void* data_ptr, const char*, const char* value, unsigned serial) {
+ WaitForPropertyData* data = reinterpret_cast<WaitForPropertyData*>(data_ptr);
+ if (*data->expected_value == value) {
+ data->done = true;
+ } else {
+ data->last_read_serial = serial;
+ }
+}
+
+void WaitForProperty(const std::string& key, const std::string& expected_value) {
+ // Find the property's prop_info*.
+ const prop_info* pi;
+ unsigned global_serial = 0;
+ 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.
+ global_serial = __system_property_wait_any(global_serial);
+ }
+
+ WaitForPropertyData data;
+ data.expected_value = &expected_value;
+ data.done = false;
+ while (true) {
+ // Check whether the property has the value we're looking for?
+ __system_property_read_callback(pi, WaitForPropertyCallback, &data);
+ if (data.done) return;
+
+ // It didn't so wait for it to change before checking again.
+ __system_property_wait(pi, data.last_read_serial);
+ }
+}
+
} // namespace base
} // namespace android