[SDK] Implement env var configuration for PeriodicExportingMetricReaderOptions

Author: mathieurobin1

sdk/include/opentelemetry/sdk/metrics/export/periodic_exporting_metric_reader_options.h

@@ -5,7 +5,6 @@
 
 #include <chrono>
 
-#include "opentelemetry/nostd/string_view.h"
 #include "opentelemetry/version.h"
 
 OPENTELEMETRY_BEGIN_NAMESPACE
@@ -17,9 +16,6 @@ namespace metrics
 constexpr std::chrono::milliseconds kExportIntervalMillis = std::chrono::milliseconds(60000);
 constexpr std::chrono::milliseconds kExportTimeOutMillis  = std::chrono::milliseconds(30000);
 
-std::chrono::milliseconds GetEnvDuration(nostd::string_view env_var_name,
-                                         std::chrono::milliseconds default_value);
-
 /**
  * Struct to hold PeriodicExortingMetricReader options.
  */

sdk/test/metrics/periodic_exporting_metric_reader_test.cc

@@ -114,41 +114,6 @@ TEST(PeriodicExportingMetricReader, Timeout)
   reader->Shutdown();
 }
 
-TEST(GetEnvDurationTest, Absent)
-{
-  const char *env = "OTEL_TEST";
-  unsetenv(env);
-  EXPECT_EQ(GetEnvDuration(env, std::chrono::milliseconds(42)), std::chrono::milliseconds(42));
-}
-
-TEST(GetEnvDurationTest, NotSet)
-{
-  const char *env = "OTEL_TEST";
-  setenv(env, "", 1);
-  EXPECT_EQ(GetEnvDuration(env, std::chrono::milliseconds(42)), std::chrono::milliseconds(42));
-  unsetenv(env);
-}
-
-TEST(GetEnvDurationTest, Valid)
-{
-  const char *env = "OTEL_TEST";
-  setenv(env, "1243ms", 1);
-  EXPECT_EQ(GetEnvDuration(env, std::chrono::milliseconds(42)), std::chrono::milliseconds(1243));
-
-  setenv(env, "3s", 1);
-  EXPECT_EQ(GetEnvDuration(env, std::chrono::milliseconds(42)), std::chrono::milliseconds(3000));
-
-  unsetenv(env);
-}
-
-TEST(GetEnvDurationTest, Invalid)
-{
-  const char *env = "OTEL_TEST";
-  setenv(env, "not_a_duration", 1);
-  EXPECT_EQ(GetEnvDuration(env, std::chrono::milliseconds(42)), std::chrono::milliseconds(42));
-  unsetenv(env);
-}
-
 TEST(PeriodicExportingMetricReaderOptions, UsesEnvVars)
 {
   const char *env_interval = "OTEL_METRIC_EXPORT_INTERVAL";