Merge "Implement android::base::WaitForProperty."
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commit
01003d40fc
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@ -58,6 +58,9 @@ template <typename T> T GetUintProperty(const std::string& key,
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// tell you whether or not your call succeeded. A `false` return value definitely means failure.
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bool SetProperty(const std::string& key, const std::string& value);
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// Waits for the system property `key` to have the value `expected_value`, .
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void WaitForProperty(const std::string& key, const std::string& expected_value);
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} // namespace base
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} // namespace android
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@ -14,9 +14,12 @@
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* limitations under the License.
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*/
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#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
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#include "android-base/properties.h"
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#include <sys/system_properties.h>
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#include <sys/_system_properties.h>
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#include <string>
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@ -78,5 +81,43 @@ bool SetProperty(const std::string& key, const std::string& value) {
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return (__system_property_set(key.c_str(), value.c_str()) == 0);
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}
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struct WaitForPropertyData {
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bool done;
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const std::string* expected_value;
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unsigned last_read_serial;
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};
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static void WaitForPropertyCallback(void* data_ptr, const char*, const char* value, unsigned serial) {
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WaitForPropertyData* data = reinterpret_cast<WaitForPropertyData*>(data_ptr);
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if (*data->expected_value == value) {
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data->done = true;
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} else {
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data->last_read_serial = serial;
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}
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}
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void WaitForProperty(const std::string& key, const std::string& expected_value) {
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// Find the property's prop_info*.
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const prop_info* pi;
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unsigned global_serial = 0;
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while ((pi = __system_property_find(key.c_str())) == nullptr) {
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// The property doesn't even exist yet.
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// Wait for a global change and then look again.
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global_serial = __system_property_wait_any(global_serial);
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}
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WaitForPropertyData data;
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data.expected_value = &expected_value;
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data.done = false;
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while (true) {
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// Check whether the property has the value we're looking for?
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__system_property_read_callback(pi, WaitForPropertyCallback, &data);
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if (data.done) return;
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// It didn't so wait for it to change before checking again.
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__system_property_wait(pi, data.last_read_serial);
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}
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}
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} // namespace base
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} // namespace android
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@ -18,7 +18,12 @@
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#include <gtest/gtest.h>
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#include <atomic>
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#include <chrono>
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#include <string>
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#include <thread>
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using namespace std::chrono_literals;
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TEST(properties, smoke) {
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android::base::SetProperty("debug.libbase.property_test", "hello");
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@ -119,3 +124,18 @@ TEST(properties, GetUintProperty_uint8_t) { CheckGetUintProperty<uint8_t>(); }
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TEST(properties, GetUintProperty_uint16_t) { CheckGetUintProperty<uint16_t>(); }
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TEST(properties, GetUintProperty_uint32_t) { CheckGetUintProperty<uint32_t>(); }
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TEST(properties, GetUintProperty_uint64_t) { CheckGetUintProperty<uint64_t>(); }
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TEST(properties, WaitForProperty) {
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std::atomic<bool> flag{false};
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std::thread thread([&]() {
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std::this_thread::sleep_for(100ms);
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android::base::SetProperty("debug.libbase.WaitForProperty_test", "a");
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while (!flag) std::this_thread::yield();
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android::base::SetProperty("debug.libbase.WaitForProperty_test", "b");
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});
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android::base::WaitForProperty("debug.libbase.WaitForProperty_test", "a");
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flag = true;
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android::base::WaitForProperty("debug.libbase.WaitForProperty_test", "b");
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thread.join();
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}
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@ -129,7 +129,7 @@ struct callback_data {
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void* cookie;
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};
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static void trampoline(void* raw_data, const char* name, const char* value) {
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static void trampoline(void* raw_data, const char* name, const char* value, unsigned /*serial*/) {
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callback_data* data = reinterpret_cast<callback_data*>(raw_data);
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data->callback(name, value, data->cookie);
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}
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