improve auth token refresh (#863)

Authentication callbacks are not thread safe, ensured call sites does single threaded calls

2 files changed, 25 insertions, 5 deletions

diff --git a/src/zenhttp/include/zenhttp/httpclient.h b/src/zenhttp/include/zenhttp/httpclient.h
index e878c900f..9531b9366 100644
--- a/src/zenhttp/include/zenhttp/httpclient.h
+++ b/src/zenhttp/include/zenhttp/httpclient.h
@@ -68,14 +68,30 @@ struct HttpClientAccessToken
 
 	static constexpr int64_t ExpireMarginInSeconds = 60 * 5;
 
-	std::string Value;
-	TimePoint	ExpireTime;
+	HttpClientAccessToken() {}
 
-	bool IsValid() const
+	HttpClientAccessToken(std::string_view InValue, const TimePoint& InExpireTime) : Value(InValue), ExpireTime(InExpireTime) {}
+
+	std::optional<std::string> GetValue() const
 	{
-		return Value.empty() == false &&
-			   ExpireMarginInSeconds < std::chrono::duration_cast<std::chrono::seconds>(ExpireTime - Clock::now()).count();
+		if (IsValid())
+		{
+			return Value;
+		}
+		return {};
 	}
+
+	bool NeedsRefresh() const
+	{
+		return Value.empty() == true || (Clock::now() + std::chrono::seconds(ExpireMarginInSeconds)) >= ExpireTime;
+	}
+
+	bool HasExpired() const { return Clock::now() >= ExpireTime; }
+	bool IsValid() const { return !Value.empty() && !HasExpired(); }
+
+private:
+	std::string Value;
+	TimePoint	ExpireTime;
 };
 
 struct HttpClientSettings
diff --git a/src/zenhttp/include/zenhttp/httpclientauth.h b/src/zenhttp/include/zenhttp/httpclientauth.h
index 26f31ed2a..f1bccdca6 100644
--- a/src/zenhttp/include/zenhttp/httpclientauth.h
+++ b/src/zenhttp/include/zenhttp/httpclientauth.h
@@ -10,6 +10,10 @@ namespace zen {
 class AuthMgr;
 
 namespace httpclientauth {
+
+	// The std::function<HttpClientAccessToken()> instances returned from these functions are not guarateed to
+	// be thread safe so caller must make sure they are not called from multiple threads in parallell
+
 	std::function<HttpClientAccessToken()> CreateFromStaticToken(HttpClientAccessToken Token);
 
 	std::function<HttpClientAccessToken()> CreateFromStaticToken(std::string_view Token);