Enhance HTTP/2 and HTTP/3 transport layer performance and streaming

- Adjust HTTP/2 flow control window update threshold for more efficient `WINDOW_UPDATE` frames.
- Optimize HPACK dynamic table lookups for header encoding by introducing an O(1) indexed cache.
- Batch multiple HTTP/2 outbound frames into a single network buffer write to reduce overhead.
- Improve HTTP/3 request body encoding to support streaming for unknown content lengths, preventing excessive memory allocation.

Author: st0o0

src/TurboHTTP.AcceptanceTests/H10/ResilienceSpec.cs

@@ -125,7 +125,7 @@ public async Task Resilience_should_fail_gracefully_on_corrupt_brotli()
         await response.Content.ReadAsByteArrayAsync(TestContext.Current.CancellationToken);
     }
 
-    [Fact(Timeout = 5000)]
+    [Fact(Timeout = 10000)]
     [Trait("RFC", "RFC1945-7.2")]
     public async Task Resilience_should_detect_truncated_body()
     {
@@ -156,7 +156,7 @@ public async Task Resilience_should_detect_truncated_body()
 
         await Assert.ThrowsAnyAsync<Exception>(async () =>
         {
-            var response = await tcs.Task.WaitAsync(TimeSpan.FromSeconds(3), TestContext.Current.CancellationToken);
+            var response = await tcs.Task.WaitAsync(TimeSpan.FromSeconds(5), TestContext.Current.CancellationToken);
             await response.Content.ReadAsStringAsync(TestContext.Current.CancellationToken);
         });
     }

src/TurboHTTP.IntegrationTests/H10/CacheSpec.cs

@@ -17,7 +17,7 @@ public CacheSpec(ServerFixture server, ActorSystemFixture systemFixture)
         _systemFixture = systemFixture;
     }
 
-    private ClientHelper CreateCacheClient(CacheStore store, CachePolicy? policy = null)
+    private ClientHelper CreateCacheClient(ICacheStore store, CachePolicy? policy = null)
     {
         return ClientHelper.CreateClient(
             _server.H1Port,
@@ -35,7 +35,7 @@ private ClientHelper CreateCacheClient(CacheStore store, CachePolicy? policy = n
     public async Task Cache_should_serve_max_age_response_from_cache()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(15));
-        var store = new CacheStore(CachePolicy.Default);
+        var store = new MemoryCacheStore();
 
         await using var helper = CreateCacheClient(store);
 
@@ -57,7 +57,7 @@ public async Task Cache_should_serve_max_age_response_from_cache()
     public async Task Cache_should_force_revalidation_with_no_cache()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(15));
-        var store = new CacheStore(CachePolicy.Default);
+        var store = new MemoryCacheStore();
 
         await using var helper = CreateCacheClient(store);
 
@@ -81,7 +81,7 @@ public async Task Cache_should_force_revalidation_with_no_cache()
     public async Task Cache_should_never_cache_no_store_response()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(20));
-        var store = new CacheStore(CachePolicy.Default);
+        var store = new MemoryCacheStore();
 
         await using var helper = CreateCacheClient(store);
 
@@ -105,7 +105,7 @@ public async Task Cache_should_never_cache_no_store_response()
     public async Task Cache_should_send_if_none_match_for_etag_revalidation()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(15));
-        var store = new CacheStore(CachePolicy.Default);
+        var store = new MemoryCacheStore();
 
         await using var helper = CreateCacheClient(store);
 
@@ -128,7 +128,7 @@ public async Task Cache_should_send_if_none_match_for_etag_revalidation()
     public async Task Cache_should_send_if_modified_since_for_last_modified_revalidation()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(15));
-        var store = new CacheStore(CachePolicy.Default);
+        var store = new MemoryCacheStore();
 
         await using var helper = CreateCacheClient(store);
 
@@ -151,7 +151,7 @@ public async Task Cache_should_send_if_modified_since_for_last_modified_revalida
     public async Task Cache_should_produce_different_entries_for_vary_header_values()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(15));
-        var store = new CacheStore(CachePolicy.Default);
+        var store = new MemoryCacheStore();
 
         await using var helper = CreateCacheClient(store);
 
@@ -187,7 +187,7 @@ public async Task Cache_should_produce_different_entries_for_vary_header_values(
     public async Task Cache_should_force_revalidation_when_must_revalidate()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(20));
-        var store = new CacheStore(CachePolicy.Default);
+        var store = new MemoryCacheStore();
 
         await using var helper = CreateCacheClient(store);
 
@@ -211,7 +211,7 @@ public async Task Cache_should_respect_s_maxage_by_shared_cache()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(15));
         var policy = new CachePolicy { SharedCache = true };
-        var store = new CacheStore(policy);
+        var store = new MemoryCacheStore();
 
         await using var helper = CreateCacheClient(store, policy);
 
@@ -232,7 +232,7 @@ public async Task Cache_should_respect_s_maxage_by_shared_cache()
     public async Task Cache_should_enable_caching_with_expires_header()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(15));
-        var store = new CacheStore(CachePolicy.Default);
+        var store = new MemoryCacheStore();
 
         await using var helper = CreateCacheClient(store);
 
@@ -253,7 +253,7 @@ public async Task Cache_should_enable_caching_with_expires_header()
     public async Task Cache_should_cache_private_response_by_private_cache()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(15));
-        var store = new CacheStore(CachePolicy.Default);
+        var store = new MemoryCacheStore();
 
         await using var helper = CreateCacheClient(store);
 
@@ -276,7 +276,7 @@ public async Task Cache_must_not_cache_private_response_by_shared_cache()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(15));
         var policy = new CachePolicy { SharedCache = true };
-        var store = new CacheStore(policy);
+        var store = new MemoryCacheStore();
 
         await using var helper = CreateCacheClient(store, policy);
 

src/TurboHTTP.IntegrationTests/H10/CookieSpec.cs

@@ -18,7 +18,7 @@ public CookieSpec(ServerFixture server, ActorSystemFixture systemFixture)
         _systemFixture = systemFixture;
     }
 
-    private ClientHelper CreateCookieClient(CookieJar jar)
+    private ClientHelper CreateCookieClient(MemoryCookieStore jar)
     {
         return ClientHelper.CreateClient(
             _server.H1Port,
@@ -31,7 +31,7 @@ private ClientHelper CreateCookieClient(CookieJar jar)
     public async Task Cookie_should_roundtrip_set_and_echo()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(15));
-        var jar = new CookieJar();
+        var jar = new MemoryCookieStore();
 
         await using var helper = CreateCookieClient(jar);
 
@@ -52,7 +52,7 @@ public async Task Cookie_should_roundtrip_set_and_echo()
     public async Task Cookie_must_not_be_sent_over_plaintext_when_secure()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(15));
-        var jar = new CookieJar();
+        var jar = new MemoryCookieStore();
 
         await using var helper = CreateCookieClient(jar);
 
@@ -73,7 +73,7 @@ public async Task Cookie_must_not_be_sent_over_plaintext_when_secure()
     public async Task Cookie_should_send_httponly_on_subsequent_requests()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(15));
-        var jar = new CookieJar();
+        var jar = new MemoryCookieStore();
 
         await using var helper = CreateCookieClient(jar);
 
@@ -97,7 +97,7 @@ public async Task Cookie_should_send_httponly_on_subsequent_requests()
     public async Task Cookie_should_store_and_send_samesite(string policy)
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(15));
-        var jar = new CookieJar();
+        var jar = new MemoryCookieStore();
 
         await using var helper = CreateCookieClient(jar);
 
@@ -118,7 +118,7 @@ public async Task Cookie_should_store_and_send_samesite(string policy)
     public async Task Cookie_should_not_be_sent_after_max_age_expires()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(25));
-        var jar = new CookieJar();
+        var jar = new MemoryCookieStore();
 
         await using var helper = CreateCookieClient(jar);
 
@@ -149,7 +149,7 @@ public async Task Cookie_should_not_be_sent_after_max_age_expires()
     public async Task Cookie_should_be_stored_when_domain_scoped()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(15));
-        var jar = new CookieJar();
+        var jar = new MemoryCookieStore();
 
         await using var helper = CreateCookieClient(jar);
 
@@ -170,7 +170,7 @@ public async Task Cookie_should_be_stored_when_domain_scoped()
     public async Task Cookie_should_be_sent_for_matching_path_when_path_scoped()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(15));
-        var jar = new CookieJar();
+        var jar = new MemoryCookieStore();
 
         await using var helper = CreateCookieClient(jar);
 
@@ -193,7 +193,7 @@ public async Task Cookie_should_be_sent_for_matching_path_when_path_scoped()
     public async Task Cookie_should_return_empty_when_no_cookies_set()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(15));
-        var jar = new CookieJar();
+        var jar = new MemoryCookieStore();
 
         await using var helper = CreateCookieClient(jar);
 
@@ -210,7 +210,7 @@ public async Task Cookie_should_return_empty_when_no_cookies_set()
     public async Task Cookie_should_store_all_multiple_setcookie_headers()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(15));
-        var jar = new CookieJar();
+        var jar = new MemoryCookieStore();
 
         await using var helper = CreateCookieClient(jar);
 
@@ -233,7 +233,7 @@ public async Task Cookie_should_store_all_multiple_setcookie_headers()
     public async Task Cookie_should_be_deleted_via_max_age_zero()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(25));
-        var jar = new CookieJar();
+        var jar = new MemoryCookieStore();
 
         await using var helper = CreateCookieClient(jar);
 
@@ -266,13 +266,13 @@ public async Task Cookie_should_be_deleted_via_max_age_zero()
     public async Task Cookie_should_persist_across_redirect_response()
     {
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(15));
-        var jar = new CookieJar();
+        var jar = new MemoryCookieStore();
 
         await using var helper = CreateCookieClient(jar);
 
         // This route sets a cookie and returns a 302 redirect to /cookie/echo.
         // Without automatic redirect following, we get the 302 back —
-        // but the CookieJar should still store the Set-Cookie from the response.
+        // but the MemoryCookieStore should still store the Set-Cookie from the response.
         var setRequest = new HttpRequestMessage(HttpMethod.Get, "/cookie/set-and-redirect");
         var setResponse = await helper.Client.SendAsync(setRequest, cts.Token);
         Assert.Equal(HttpStatusCode.Found, setResponse.StatusCode);

src/TurboHTTP.IntegrationTests/H11/HandlerPipelineSpec.cs

@@ -211,7 +211,7 @@ public async Task HandlerPipeline_should_work_with_cookie_pipeline()
         // UseRequest injects X-From-Handler.
         // WithCookies causes the jar to inject a Cookie header on subsequent requests.
         // /interaction/echo-all-headers echoes X-* headers AND Cookie as X-Received-Cookie.
-        var jar = new CookieJar();
+        var jar = new MemoryCookieStore();
 
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
         await using var helper = ClientHelper.CreateClient(

src/TurboHTTP.IntegrationTests/H3/HandlerPipelineSpec.cs

@@ -221,7 +221,7 @@ public async Task HandlerPipeline_should_work_with_compression_pipeline()
     [Fact(Timeout = 20000)]
     public async Task HandlerPipeline_should_work_with_cookie_pipeline()
     {
-        var jar = new CookieJar();
+        var jar = new MemoryCookieStore();
 
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
         await using var helper = ClientHelper.CreateClient(