466ec4e632
This is part one of a mult-part change to revise some metrics. Several metrics are currently EventMetric type when they should be a simpler type. Test: Added unit tests for the new types. Also, re-ran existing tests. Verified playback works with Google Play, and re-ran Widevine GTS tests. Bug: 36220619 Change-Id: I2ec8fc355f66ad4834dd722aacd22541fb9c94ad
126 lines
4.4 KiB
C++
126 lines
4.4 KiB
C++
// Copyright 2017 Google Inc. All Rights Reserved.
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//
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// This file contains the helper classes and methods for using field tuples
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// used by metrics classes to record variations of a single metric.
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#ifndef WVCDM_METRICS_FIELD_TUPLES_H_
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#define WVCDM_METRICS_FIELD_TUPLES_H_
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#include <cstdarg>
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#include <memory>
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#include <ostream>
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#include <sstream>
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#include <stdint.h>
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#include <string>
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#include <vector>
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namespace wvcdm {
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namespace metrics {
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namespace util {
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// This is a placeholder type for unused type parameters. It aids in supporting
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// templated classes with "variable" type arguments.
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struct Unused {
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// Required for compilation. Should never be used.
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inline friend std::ostream& operator<< (std::ostream& out, const Unused&)
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{ return out; }
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};
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// This utility method formats the collection of field name/value pairs.
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// The format of the string is:
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//
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// [{field:value[&field:value]*}]
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//
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// If there are no pairs, returns a blank string.
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template<typename F1, typename F2, typename F3, typename F4>
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std::string MakeFieldNameString(const std::vector<std::string>& field_names,
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const F1 field1, const F2 field2,
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const F3 field3, const F4 field4) {
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std::stringstream field_name_and_values;
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std::vector<std::string>::const_iterator field_name_iterator =
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field_names.begin();
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if (field_name_iterator == field_names.end()) {
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return field_name_and_values.str();
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}
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// There is at least one name/value pair. Prepend open brace.
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field_name_and_values << "{";
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field_name_and_values << *field_name_iterator << ':' << field1;
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if (++field_name_iterator == field_names.end()) {
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field_name_and_values << "}";
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return field_name_and_values.str();
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}
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field_name_and_values << '&' << *field_name_iterator << ':' << field2;
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if (++field_name_iterator == field_names.end()) {
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field_name_and_values << "}";
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return field_name_and_values.str();
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}
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field_name_and_values << '&' << *field_name_iterator << ':' << field3;
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if (++field_name_iterator == field_names.end()) {
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field_name_and_values << "}";
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return field_name_and_values.str();
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}
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field_name_and_values << '&' << *field_name_iterator << ':' << field4;
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field_name_and_values << "}";
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return field_name_and_values.str();
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}
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// This specialization of the helper method is a shortcut for class
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// instances with no fields.
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template<>
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inline std::string MakeFieldNameString<Unused, Unused, Unused, Unused>(
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const std::vector<std::string>& /* field_names */,
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const Unused /* unused1 */, const Unused /* unused2 */,
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const Unused /* unused3 */, const Unused /* unused4 */) {
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return "";
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}
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// This helper function appends the field names to a vector of strings.
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inline void AppendFieldNames(std::vector<std::string>* field_name_vector,
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int field_count, ...) {
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va_list field_names;
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va_start(field_names, field_count);
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for (int x = 0; x < field_count; x++) {
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field_name_vector->push_back(va_arg(field_names, const char*));
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}
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va_end(field_names);
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}
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// These helper methods and FirstUnusedType assure that there is no mismatch
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// between the specified types for metrics type parameters and the constructors
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// and methods used for the specializations.
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template <bool>
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struct CompileAssert {};
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#define COMPILE_ASSERT(expr, msg) \
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typedef util::CompileAssert<(bool(expr))> msg[bool(expr) ? 1 : -1]
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template <typename T> struct is_unused { static const bool value = false; };
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template <> struct is_unused<Unused> { static const bool value = true; };
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template <typename F1, typename F2, typename F3, typename F4>
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class FirstUnusedType {
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static const bool a = is_unused<F1>::value;
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static const bool b = is_unused<F2>::value;
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static const bool c = is_unused<F3>::value;
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static const bool d = is_unused<F4>::value;
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// Check that all types after the first Unused are also Unused.
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COMPILE_ASSERT(a <= b, Invalid_Unused_At_Position_2);
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COMPILE_ASSERT(b <= c, Invalid_Unused_At_Position_3);
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COMPILE_ASSERT(c <= d, Invalid_Unused_At_Position_4);
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public:
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static const int value = 5 - (a + b + c + d);
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};
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// Asserts that no Unused types exist before N; after N, are all Unused types.
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#define ASSERT_METRIC_UNUSED_START_FROM(N) \
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COMPILE_ASSERT((\
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util::FirstUnusedType<F1, F2, F3, F4>::value) == N, \
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Unused_Start_From_##N)
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} // namespace util
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} // namespace metrics
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} // namespace wvcdm
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#endif // WVCDM_METRICS_FIELD_TUPLES_H_
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