[Repo Assist] fix: reuse SocketsHttpHandler to prevent SNAT port exhaustion

src/FsHttp/Defaults.fs

@@ -10,40 +10,68 @@ open System.Text.Json
 let defaultJsonDocumentOptions = JsonDocumentOptions()
 let defaultJsonSerializerOptions = JsonSerializerOptions JsonSerializerDefaults.Web
 
-let defaultHttpClientFactory (config: Config) =
-    let handler =
+let defaultDecompressionMethods = [ DecompressionMethods.All ]
+
+// A long-lived shared handler used when no handler customisations are required.
+// Reusing a single SocketsHttpHandler preserves the TCP connection pool across requests,
+// preventing SNAT port exhaustion on Azure and similar environments (issue #198).
+// The HttpClient created per-request uses disposeHandler=false so the pool is never torn down.
+let private sharedDefaultHandler =
+    lazy (
+        let decompression = defaultDecompressionMethods |> List.fold (fun c n -> c ||| n) DecompressionMethods.None
         new SocketsHttpHandler(
-            UseCookies = false, 
-            PooledConnectionLifetime = TimeSpan.FromMinutes 5.0)
-    let ignoreSslIssues =
-        match config.certErrorStrategy with
-        | Default -> false
-        | AlwaysAccept -> true
-    if ignoreSslIssues then
-        do handler.SslOptions <-
-            let options = Security.SslClientAuthenticationOptions()
-            let callback = Security.RemoteCertificateValidationCallback(fun sender cert chain errors -> true)
-            do options.RemoteCertificateValidationCallback <- callback
-            options
-    do handler.AutomaticDecompression <-
-        config.defaultDecompressionMethods
-        |> List.fold (fun c n -> c ||| n) DecompressionMethods.None
-    let handler = config.httpClientHandlerTransformers |> List.fold (fun c n -> n c) handler
+            UseCookies = false,
+            PooledConnectionLifetime = TimeSpan.FromMinutes 5.0,
+            AutomaticDecompression = decompression))
 
-    match config.proxy with
-    | Some proxy ->
-        let webProxy = WebProxy(proxy.url)
+let private canUseSharedHandler (config: Config) =
+    config.certErrorStrategy = Default
+    && List.isEmpty config.httpClientHandlerTransformers
+    && config.proxy.IsNone
+    && config.defaultDecompressionMethods = defaultDecompressionMethods
+
+let defaultHttpClientFactory (config: Config) =
+    let handler, disposeHandler =
+        if canUseSharedHandler config then
+            // Return the shared handler without ownership.
+            // The per-request HttpClient is a lightweight wrapper; only the handler holds connections.
+            sharedDefaultHandler.Value, false
+        else
+            let handler =
+                new SocketsHttpHandler(
+                    UseCookies = false,
+                    PooledConnectionLifetime = TimeSpan.FromMinutes 5.0)
+            let ignoreSslIssues =
+                match config.certErrorStrategy with
+                | Default -> false
+                | AlwaysAccept -> true
+            if ignoreSslIssues then
+                do handler.SslOptions <-
+                    let options = Security.SslClientAuthenticationOptions()
+                    let callback = Security.RemoteCertificateValidationCallback(fun sender cert chain errors -> true)
+                    do options.RemoteCertificateValidationCallback <- callback
+                    options
+            do handler.AutomaticDecompression <-
+                config.defaultDecompressionMethods
+                |> List.fold (fun c n -> c ||| n) DecompressionMethods.None
+            let handler = config.httpClientHandlerTransformers |> List.fold (fun c n -> n c) handler
 
-        match proxy.credentials with
-        | Some cred ->
-            webProxy.UseDefaultCredentials <- false
-            webProxy.Credentials <- cred
-        | None -> webProxy.UseDefaultCredentials <- true
+            match config.proxy with
+            | Some proxy ->
+                let webProxy = WebProxy(proxy.url)
 
-        handler.Proxy <- webProxy
-    | None -> ()
+                match proxy.credentials with
+                | Some cred ->
+                    webProxy.UseDefaultCredentials <- false
+                    webProxy.Credentials <- cred
+                | None -> webProxy.UseDefaultCredentials <- true
 
-    let client = new HttpClient(handler)
+                handler.Proxy <- webProxy
+            | None -> ()
+
+            handler, true
+
+    let client = new HttpClient(handler, disposeHandler)
     do config.timeout |> Option.iter (fun timeout -> client.Timeout <- timeout)
     client
 
@@ -52,9 +80,7 @@ let defaultHeadersAndBodyPrintMode = {
     maxLength = Some 7000
 }
 
-let defaultDecompressionMethods = [ DecompressionMethods.All ]
-
-let defaultConfig = 
+let defaultConfig =
     {
         timeout = None
         defaultDecompressionMethods = defaultDecompressionMethods