PM: Generic variable for copying the return value of a function call.
This is useful for quickly implementing variables that rely on calls to
utility functions/methods.
BUG=None
TEST=Unit tests.
Change-Id: I46040070c417b8c1f7b6081d4fe4d3b43a7a8101
Reviewed-on: https://chromium-review.googlesource.com/200659
Reviewed-by: Gilad Arnold <garnold@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
diff --git a/policy_manager/generic_variables.h b/policy_manager/generic_variables.h
index 5309519..42e991d 100644
--- a/policy_manager/generic_variables.h
+++ b/policy_manager/generic_variables.h
@@ -9,6 +9,8 @@
#ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_POLICY_MANAGER_GENERIC_VARIABLES_H_
#define CHROMEOS_PLATFORM_UPDATE_ENGINE_POLICY_MANAGER_GENERIC_VARIABLES_H_
+#include <base/callback.h>
+
#include "update_engine/policy_manager/variable.h"
namespace {
@@ -118,6 +120,37 @@
const T obj_;
};
+// Variable class returning a copy of a value returned by a given function. The
+// function is called every time the variable is being polled.
+template<typename T>
+class CallCopyVariable : public Variable<T> {
+ public:
+ CallCopyVariable(const std::string& name, base::Callback<T(void)> func)
+ : Variable<T>(name, kVariableModePoll), func_(func) {}
+ CallCopyVariable(const std::string& name,
+ const base::TimeDelta poll_interval,
+ base::Callback<T(void)> func)
+ : Variable<T>(name, poll_interval), func_(func) {}
+
+ protected:
+ // Variable override.
+ virtual const T* GetValue(base::TimeDelta /* timeout */,
+ std::string* /* errmsg */) {
+ if (func_.is_null())
+ return nullptr;
+ return new T(func_.Run());
+ }
+
+ private:
+ FRIEND_TEST(PmCallCopyVariableTest, SimpleTest);
+
+ // The function to be called, stored as a base::Callback.
+ base::Callback<T(void)> func_;
+
+ DISALLOW_COPY_AND_ASSIGN(CallCopyVariable);
+};
+
+
// A Variable class to implement simple Async variables. It provides two methods
// SetValue and UnsetValue to modify the current value of the variable and
// notify the registered observers whenever the value changed.
diff --git a/policy_manager/generic_variables_unittest.cc b/policy_manager/generic_variables_unittest.cc
index 8aad753..279c729 100644
--- a/policy_manager/generic_variables_unittest.cc
+++ b/policy_manager/generic_variables_unittest.cc
@@ -4,6 +4,7 @@
#include "update_engine/policy_manager/generic_variables.h"
+#include <base/callback.h>
#include <base/memory/scoped_ptr.h>
#include <gtest/gtest.h>
@@ -57,11 +58,14 @@
class CopyConstructorTestClass {
public:
CopyConstructorTestClass(void) : copied_(false) {}
- CopyConstructorTestClass(const CopyConstructorTestClass& /* ignored */)
- : copied_(true) {}
+ CopyConstructorTestClass(const CopyConstructorTestClass& other)
+ : copied_(true), val_(other.val_ * 2) {}
// Tells if the instance was constructed using the copy-constructor.
- bool copied_;
+ const bool copied_;
+
+ // An auxiliary internal value.
+ int val_ = 0;
};
@@ -91,6 +95,41 @@
}
+class PmCallCopyVariableTest : public ::testing::Test {};
+
+CopyConstructorTestClass test_func(CopyConstructorTestClass* obj) {
+ obj->val_++; // So we can check that the function was called.
+ return *obj;
+}
+
+TEST_F(PmCallCopyVariableTest, SimpleTest) {
+ // Tests that the returned value is generated by copying the value returned by
+ // the function call.
+
+ CopyConstructorTestClass test_obj;
+ ASSERT_FALSE(test_obj.copied_);
+ test_obj.val_ = 5;
+
+ base::Callback<CopyConstructorTestClass(void)> cb = base::Bind(
+ test_func, &test_obj);
+ CallCopyVariable<CopyConstructorTestClass> var("var", cb);
+
+ scoped_ptr<const CopyConstructorTestClass> copy(
+ var.GetValue(PmTestUtils::DefaultTimeout(), nullptr));
+ EXPECT_EQ(6, test_obj.val_); // Check that the function was called.
+ PMTEST_ASSERT_NOT_NULL(copy.get());
+ EXPECT_TRUE(copy->copied_);
+ EXPECT_EQ(12, copy->val_); // Check that copying occurred once.
+}
+
+TEST_F(PmCallCopyVariableTest, NullTest) {
+ // Ensures that the variable returns null when the callback is null.
+
+ base::Callback<bool(void)> cb;
+ CallCopyVariable<bool> var("var", cb);
+ PmTestUtils::ExpectVariableNotSet(&var);
+}
+
class PmAsyncCopyVariableTest : public ::testing::Test {
public:
void TearDown() {