1 files changed, 122 insertions, 0 deletions
diff --git a/toolkit/components/processtools/tests/xpcshell/test_total_cpu_time.js b/toolkit/components/processtools/tests/xpcshell/test_total_cpu_time.js
new file mode 100644
index 0000000000..00f1ea2b6c
--- /dev/null
+++ b/toolkit/components/processtools/tests/xpcshell/test_total_cpu_time.js
@@ -0,0 +1,122 @@
+"use strict";
+
+var cpuThreadCount;
+
+add_task(async function setup() {
+  // FOG needs a profile directory to put its data in.
+  do_get_profile();
+
+  Services.fog.initializeFOG();
+
+  cpuThreadCount = (await Services.sysinfo.processInfo).count;
+});
+
+async function getCpuTimeFromProcInfo() {
+  const NS_PER_MS = 1000000;
+  let cpuTimeForProcess = p => p.cpuTime / NS_PER_MS;
+  let procInfo = await ChromeUtils.requestProcInfo();
+  return (
+    cpuTimeForProcess(procInfo) +
+    procInfo.children.map(cpuTimeForProcess).reduce((a, b) => a + b, 0)
+  );
+}
+
+add_task(async function test_totalCpuTime_in_parent() {
+  let startTime = Date.now();
+
+  let initialProcInfoCpuTime = Math.floor(await getCpuTimeFromProcInfo());
+  await Services.fog.testFlushAllChildren();
+
+  let initialCpuTime = Glean.power.totalCpuTimeMs.testGetValue();
+  Assert.greater(
+    initialCpuTime,
+    0,
+    "The CPU time used by starting the test harness should be more than 0"
+  );
+  let initialProcInfoCpuTime2 = Math.ceil(await getCpuTimeFromProcInfo());
+
+  Assert.greaterOrEqual(
+    initialCpuTime,
+    initialProcInfoCpuTime,
+    "The CPU time reported through Glean should be at least as much as the CPU time reported by ProcInfo before asking Glean for the data"
+  );
+  Assert.lessOrEqual(
+    initialCpuTime,
+    initialProcInfoCpuTime2,
+    "The CPU time reported through Glean should be no more than the CPU time reported by ProcInfo after asking Glean for the data"
+  );
+
+  // 50 is an arbitrary value, but the resolution is 16ms on Windows,
+  // so this needs to be significantly more than 16.
+  const kBusyWaitForMs = 50;
+  while (Date.now() - startTime < kBusyWaitForMs) {
+    // Burn CPU time...
+  }
+
+  let additionalProcInfoCpuTime =
+    Math.floor(await getCpuTimeFromProcInfo()) - initialProcInfoCpuTime2;
+  await Services.fog.testFlushAllChildren();
+
+  let additionalCpuTime =
+    Glean.power.totalCpuTimeMs.testGetValue() - initialCpuTime;
+  info(
+    `additional CPU time according to ProcInfo: ${additionalProcInfoCpuTime}ms and Glean ${additionalCpuTime}ms`
+  );
+
+  // On a machine where the CPU is very busy, our busy wait loop might burn less
+  // CPU than expected if other processes are being scheduled instead of us.
+  let expectedAdditionalCpuTime = Math.min(
+    additionalProcInfoCpuTime,
+    kBusyWaitForMs
+  );
+  Assert.greaterOrEqual(
+    additionalCpuTime,
+    expectedAdditionalCpuTime,
+    `The total CPU time should have increased by at least ${expectedAdditionalCpuTime}ms`
+  );
+  let wallClockTime = Date.now() - startTime;
+  Assert.lessOrEqual(
+    additionalCpuTime,
+    wallClockTime * cpuThreadCount,
+    `The total CPU time should have increased by at most the wall clock time (${wallClockTime}ms) * ${cpuThreadCount} CPU threads`
+  );
+});
+
+add_task(async function test_totalCpuTime_in_child() {
+  const MESSAGE_CHILD_TEST_DONE = "ChildTest:Done";
+
+  let startTime = Date.now();
+  await Services.fog.testFlushAllChildren();
+  let initialCpuTime = Glean.power.totalCpuTimeMs.testGetValue();
+
+  let initialProcInfoCpuTime = await getCpuTimeFromProcInfo();
+  run_test_in_child("test_total_cpu_time_child.js");
+  let burntCpuTime = await do_await_remote_message(MESSAGE_CHILD_TEST_DONE);
+  let additionalProcInfoCpuTime =
+    (await getCpuTimeFromProcInfo()) - initialProcInfoCpuTime;
+
+  await Services.fog.testFlushAllChildren();
+  let additionalCpuTime =
+    Glean.power.totalCpuTimeMs.testGetValue() - initialCpuTime;
+  info(
+    `additional CPU time according to ProcInfo: ${additionalProcInfoCpuTime}ms and Glean ${additionalCpuTime}ms`
+  );
+
+  // On a machine where the CPU is very busy, our busy wait loop might burn less
+  // CPU than expected if other processes are being scheduled instead of us.
+  let expectedAdditionalCpuTime = Math.min(
+    Math.floor(additionalProcInfoCpuTime),
+    burntCpuTime
+  );
+  Assert.greaterOrEqual(
+    additionalCpuTime,
+    expectedAdditionalCpuTime,
+    `The total CPU time should have increased by at least ${expectedAdditionalCpuTime}ms`
+  );
+  let wallClockTime = Date.now() - startTime;
+  Assert.lessOrEqual(
+    additionalCpuTime,
+    wallClockTime * cpuThreadCount,
+    `The total CPU time should have increased by at most the wall clock time (${wallClockTime}ms) * ${cpuThreadCount} CPU threads`
+  );
+});