server: add SSE ping interval (#24013)

common/arg.cpp

@@ -3027,6 +3027,13 @@ common_params_context common_params_parser_init(common_params & params, llama_ex
             params.timeout_write = value;
         }
     ).set_examples({LLAMA_EXAMPLE_SERVER}).set_env("LLAMA_ARG_TIMEOUT"));
+    add_opt(common_arg(
+        {"--sse-ping-interval"}, "N",
+        string_format("server SSE ping interval in seconds (-1 = disabled, default: %d)", params.sse_ping_interval),
+        [](common_params & params, int value) {
+            params.sse_ping_interval = value;
+        }
+    ).set_examples({LLAMA_EXAMPLE_SERVER}).set_env("LLAMA_ARG_SSE_PING_INTERVAL"));
     add_opt(common_arg(
         {"--threads-http"}, "N",
         string_format("number of threads used to process HTTP requests (default: %d)", params.n_threads_http),

common/common.h

@@ -592,6 +592,7 @@ struct common_params {
     bool    reuse_port          = false;         // allow multiple sockets to bind to the same port
     int32_t timeout_read        = 3600;          // http read timeout in seconds
     int32_t timeout_write       = timeout_read;  // http write timeout in seconds
+    int32_t sse_ping_interval   = 30;            // SSE ping interval in seconds
     int32_t n_threads_http      = -1;    // number of threads to process HTTP requests (TODO: support threadpool)
     int32_t n_cache_reuse       = 0;     // min chunk size to reuse from the cache via KV shifting
     bool    cache_prompt        = true;  // whether to enable prompt caching