Fix timeouts for android::base::WaitForProperty*

std::chrono doesn't handle integer overflow, so using
std::chrono::milliseconds::max() to indicate an infinite timeout is
not handled well in the current code.  It causes an 'absolute_timeout'
earlier in time than 'now' and causes the associated WaitForProperty*
functions to return immediately.

Also, any duration_cast from relative_timeout to nanoseconds would
cause the same issue, as it would overflow in the conversion and
result in an invalid results.

This change prevents any duration_casts of relative_timeout to
nanoseconds and replaces the logic to wait on an absolute timeout with
logic that compares the time elapsed to the provided relative timeout.

This change also includes a test that std::chrono::milliseconds::max()
does not return immediately and that negative values do return immediately.

Test: Boot bullhead + libbase_test

Change-Id: I335bfa7ba71e86c20119a0ed46014cad44361162

1 files changed, 32 insertions, 0 deletions

diff --git a/base/properties_test.cpp b/base/properties_test.cpp
index 1bbe48249..de5f3dcfa 100644
--- a/base/properties_test.cpp
+++ b/base/properties_test.cpp
@@ -151,6 +151,38 @@ TEST(properties, WaitForProperty_timeout) {
   ASSERT_LT(std::chrono::duration_cast<std::chrono::milliseconds>(t1 - t0), 600ms);
 }
 
+TEST(properties, WaitForProperty_MaxTimeout) {
+  std::atomic<bool> flag{false};
+  std::thread thread([&]() {
+    android::base::SetProperty("debug.libbase.WaitForProperty_test", "a");
+    while (!flag) std::this_thread::yield();
+    std::this_thread::sleep_for(500ms);
+    android::base::SetProperty("debug.libbase.WaitForProperty_test", "b");
+  });
+
+  ASSERT_TRUE(android::base::WaitForProperty("debug.libbase.WaitForProperty_test", "a", 1s));
+  flag = true;
+  // Test that this does not immediately return false due to overflow issues with the timeout.
+  ASSERT_TRUE(android::base::WaitForProperty("debug.libbase.WaitForProperty_test", "b"));
+  thread.join();
+}
+
+TEST(properties, WaitForProperty_NegativeTimeout) {
+  std::atomic<bool> flag{false};
+  std::thread thread([&]() {
+    android::base::SetProperty("debug.libbase.WaitForProperty_test", "a");
+    while (!flag) std::this_thread::yield();
+    std::this_thread::sleep_for(500ms);
+    android::base::SetProperty("debug.libbase.WaitForProperty_test", "b");
+  });
+
+  ASSERT_TRUE(android::base::WaitForProperty("debug.libbase.WaitForProperty_test", "a", 1s));
+  flag = true;
+  // Assert that this immediately returns with a negative timeout
+  ASSERT_FALSE(android::base::WaitForProperty("debug.libbase.WaitForProperty_test", "b", -100ms));
+  thread.join();
+}
+
 TEST(properties, WaitForPropertyCreation) {
   std::thread thread([&]() {
     std::this_thread::sleep_for(100ms);