Merge pull request #233 from barspi/HttpQuery-maxConnections

HttpQuery: increasing default number of connections...

doc/src/asciidoc/module_http_client.adoc

@@ -36,6 +36,9 @@ The `HttpQuery` participant has the following configuration properties:
 * `preemptiveAuth`: if doing Basic Authentication (by presence of context value), do it on the first request (default `false`)
 * `responseBodyOnError`: should an HTTP response body be included for responses with error
    status code? (`boolean`, default `false`);
+* `maxConnections`: set the maximum number of concurrent client connections; if unset it will default to **25** concurrent connetions.+
+   **NOTE:** This value is overridable by the `http.maxConnections` Java system property, and it applies globally to the whole process.
+
 
 In addition, `HttpQuery` picks a few _configurable_ entries from the `Context`:
 
@@ -52,8 +55,8 @@ In addition, `HttpQuery` picks a few _configurable_ entries from the `Context`:
    ** a `String[]` where each item follows the `header_name:header_value` syntax
    ** a `List<String>` where each item follows the `header_name:header_value` syntax
    ** a `Map<String,String>` where the keys represent _header names_, and the values the corresponding _header values_
-* `.HTTP_BASIC_AUTHENTICATION`: A String of the form `<username>:<password>` used for HTTP Basic Authentication.
-   NOTE: The default `Context` name starts with a period (`.`), meaning it will be hidden in the logs during a context dump.
+* `.HTTP_BASIC_AUTHENTICATION`: A String of the form `<username>:<password>` used for HTTP Basic Authentication. +
+   **NOTE:** The default `Context` name starts with a period (`.`), meaning it will be hidden in the logs during a context dump.
 
 After successful completion (which may include normal HTTP errors such as `404` or `500`), `HttpQuery` stores the result
 back into the `Context`:

modules/http-client/src/main/java/org/jpos/http/client/HttpQuery.java

@@ -77,6 +77,8 @@
 
 @SuppressWarnings("unused")
 public class HttpQuery extends Log implements AbortParticipant, Configurable, Destroyable {
+    private static final String DEFAULT_MAX_CONNECTIONS = "25";         // overridable by sys prop http.maxConnections, or with cfg "maxConnections"
+
     private static final int DEFAULT_CONNECT_TIMEOUT = 10000;
     private static final int DEFAULT_TIMEOUT = 15000;
 
@@ -261,9 +263,27 @@ else if ("lax".equals(redirProp))
             redirectStrategy= LaxRedirectStrategy.INSTANCE;
         else
             throw new ConfigurationException("'redirect-strategy' must be 'lax' or 'default'");
+
+
+        String maxConn = System.getProperty("http.maxConnections");
+        if (maxConn == null || maxConn.trim().isEmpty()) {
+            String maxConnCfg = cfg.get("maxConnections", DEFAULT_MAX_CONNECTIONS);
+            maxConn = maxConnCfg.trim();
+            System.setProperty("http.maxConnections", maxConn);
+        }
+        try { Integer.parseInt(maxConn); }
+        catch (Exception e) {
+            throw new ConfigurationException("Bad value for maxConnections: "+maxConn);
+        }
     }
 
-    public CloseableHttpAsyncClient getHttpClient(boolean trustAllCerts) {
+
+    /**
+        Method is synchronized against this instance of HttpQuery, because the instance of
+        the CloseableHttpAsyncClient is *lazily* created upon first request, and only one
+        should be created and shared by all threads.
+    */
+    public synchronized CloseableHttpAsyncClient getHttpClient(boolean trustAllCerts) {
         if (trustAllCerts) {
             if (unsecureHttpClient == null) {
                 setUnsecureHttpClient(getClientBuilder(true).build());
@@ -291,6 +311,7 @@ protected HttpAsyncClientBuilder getClientBuilder(boolean trustAllCerts) {
         if (trustAllCerts) {
             disableSSLVerification(builder);
         }
+
         return builder;
     }