[V4] Re-introduce background refresh behavior (#4100)

* Rework the locking in the RefreshingAWSCredentials base class
* Add backwardIncompatibilitiesToIgnore to change log
* refactor: Re-introduce unit tests for background refresh
* refactor: Update logging to remove duplicate messages and use correct timestamps
* fix: Mark method as static
* refactor: Address Copilot feedback
* refactor: More test cases and documentation updates
* Add locking documentation for RefreshingAWSCredentials

---------

Co-authored-by: Norm Johanson <[email protected]>

Author: dscpinheiro

generator/.DevConfigs/e11928c9-15fb-4b9e-91d3-91775150d378.json

@@ -0,0 +1,13 @@
+{
+  "core": {
+    "updateMinimum": true,
+    "type": "minor",
+    "changeLogMessages": [
+      "Re-introduce background refresh of credentials during their preempt expiry period (https://github.com/aws/aws-sdk-net/issues/4024)"
+    ],
+    "backwardIncompatibilitiesToIgnore": [
+      "Amazon.Runtime.RefreshingAWSCredentials/MethodAdded",
+      "Amazon.Runtime.RefreshingAWSCredentials/FieldTypeChanged"
+    ]
+  }
+}

sdk/src/Core/Amazon.Runtime/Credentials/InstanceProfileAWSCredentials.cs

@@ -91,10 +91,7 @@ protected override CredentialsRefreshState GenerateNewCredentials()
                 // but try again to refresh them in 2 minutes.
                 if (null != _currentRefreshState)
                 {
-#pragma warning disable CS0612, CS0618 // Type or member is obsolete
-                    var newExpiryTime = AWSSDKUtils.CorrectedUtcNow + TimeSpan.FromMinutes(2);
-#pragma warning restore CS0612,CS0618 // Type or member is obsolete
-
+                    var newExpiryTime = _timeProvider.CorrectedUtcNow + TimeSpan.FromMinutes(2);
                     _currentRefreshState = new CredentialsRefreshState(_currentRefreshState.Credentials, newExpiryTime);
                     return _currentRefreshState;
                 }
@@ -107,10 +104,7 @@ protected override CredentialsRefreshState GenerateNewCredentials()
 
                 // use a custom refresh time
 
-#pragma warning disable CS0612, CS0618 // Type or member is obsolete
-                var newExpiryTime = AWSSDKUtils.CorrectedUtcNow + TimeSpan.FromMinutes(new Random().Next(5, 11));
-#pragma warning restore CS0612, CS0618 // Type or member is obsolete
-
+                var newExpiryTime = _timeProvider.CorrectedUtcNow + TimeSpan.FromMinutes(new Random().Next(5, 11));
                 _currentRefreshState = new CredentialsRefreshState(newState.Credentials, newExpiryTime);
 
                 return _currentRefreshState;
@@ -175,7 +169,7 @@ protected override async Task<CredentialsRefreshState> GenerateNewCredentialsAsy
                 // but try again to refresh them in 2 minutes.
                 if (null != _currentRefreshState)
                 {
-                    var newExpiryTime = AWSSDKUtils.CorrectedUtcNow + TimeSpan.FromMinutes(2);
+                    var newExpiryTime = _timeProvider.CorrectedUtcNow + TimeSpan.FromMinutes(2);
                     _currentRefreshState = new CredentialsRefreshState(_currentRefreshState.Credentials, newExpiryTime);
                     return _currentRefreshState;
                 }
@@ -187,7 +181,7 @@ protected override async Task<CredentialsRefreshState> GenerateNewCredentialsAsy
                 _logger.InfoFormat(_receivedExpiredCredentialsFromIMDS);
 
                 // use a custom refresh time
-                var newExpiryTime = AWSSDKUtils.CorrectedUtcNow + TimeSpan.FromMinutes(new Random().Next(5, 11));
+                var newExpiryTime = _timeProvider.CorrectedUtcNow + TimeSpan.FromMinutes(new Random().Next(5, 11));
                 _currentRefreshState = new CredentialsRefreshState(newState.Credentials, newExpiryTime);
 
                 return _currentRefreshState;
@@ -396,7 +390,7 @@ private static Uri InfoUri
 
         private CredentialsRefreshState GetEarlyRefreshState(CredentialsRefreshState state)
         {
-            DateTime newExpiryTime = AWSSDKUtils.CorrectedUtcNow + _refreshAttemptPeriod + PreemptExpiryTime;
+            DateTime newExpiryTime = _timeProvider.CorrectedUtcNow + _refreshAttemptPeriod + PreemptExpiryTime;
 
             // Use this only if the time is earlier than the default expiration time
             if (newExpiryTime > state.Expiration)