implement multiple linear chain

runtime/src/module.c

@@ -405,6 +405,7 @@ module_new_from_json(char *file_name)
 		uint32_t expected_execution_us                               = 0;
 		int      admissions_percentile                               = 50;
 		bool     is_active                                           = false;
+		bool     is_tail_module                                      = false;
 		int32_t  request_count                                       = 0;
 		int32_t  response_count                                      = 0;
 		int      j                                                   = 1;
@@ -453,6 +454,15 @@ module_new_from_json(char *file_name)
 				} else {
 					panic("Expected active key to be a JSON boolean, was %s\n", val);
 				}
+			} else if (strcmp(key, "tail_module") == 0) {
+				assert(tokens[i + j + 1].type == JSMN_PRIMITIVE);
+                                if (val[0] == 't') {
+                                        is_tail_module = true;
+                                } else if (val[0] == 'f') {
+                                        is_tail_module = false;
+                                } else {
+                                        panic("Expected tail_module key to be a JSON boolean, was %s\n", val);
+                                }
 			} else if (strcmp(key, "relative-deadline-us") == 0) {
 				int64_t buffer = strtoll(val, NULL, 10);
 				if (buffer < 0 || buffer > (int64_t)RUNTIME_RELATIVE_DEADLINE_US_MAX)
@@ -563,6 +573,11 @@ module_new_from_json(char *file_name)
 			tail_module			= module;
 			tail_module->next_module 	= NULL;
 
+			/* if this is the tail module, reset tail_module to NULL to build another new chain */		
+			if (is_tail_module) {
+				tail_module = NULL;
+			}
+	
 			module_set_http_info(module, request_count, request_headers, request_content_type,
 			                     response_count, reponse_headers, response_content_type);
 			module_count++;

runtime/tests/mulitple_linear_chain.json

@@ -0,0 +1,90 @@
+{
+  "active": true,
+  "name": "resize",
+  "path": "resize_wasm.so",
+  "port": 10000,
+  "relative-deadline-us": 50000,
+  "argsize": 1,
+  "http-req-headers": [],
+  "http-req-content-type": "image/jpeg",
+  "http-req-size": 1024000,
+  "http-resp-headers": [],
+  "http-resp-size": 1024000,
+  "http-resp-content-type": "image/png"
+},
+{
+  "active": true,
+  "name": "png2bmp",
+  "path": "C-Image-Manip_wasm.so",
+  "port": 10001,
+  "relative-deadline-us": 60000,
+  "argsize": 1,
+  "http-req-headers": [],
+  "http-req-content-type": "image/png",
+  "http-req-size": 4096000,
+  "http-resp-headers": [],
+  "http-resp-size": 4096000,
+  "http-resp-content-type": "image/bmp"
+},
+{
+  "active": true,
+  "name": "cifar10",
+  "path": "cifar10_wasm.so",
+  "port": 10002,
+  "relative-deadline-us": 50000,
+  "argsize": 1,
+  "http-req-headers": [],
+  "http-req-content-type": "image/bmp",
+  "http-req-size": 4096000,
+  "http-resp-headers": [],
+  "http-resp-size": 1024,
+  "http-resp-content-type": "text/plain",
+  "tail-module": true
+},
+{
+  "active": true,
+  "name": "fibonacci",
+  "path": "fibonacci_wasm.so",
+  "port": 10003,
+  "expected-execution-us": 600,
+  "relative-deadline-us": 2000,
+  "argsize": 2,
+  "http-req-headers": [],
+  "http-req-content-type": "text/plain",
+  "http-req-size": 1024,
+  "http-resp-headers": [],
+  "http-resp-size": 1024,
+  "http-resp-content-type": "text/plain"
+},
+{
+  "active": true,
+  "name": "fibonacci2",
+  "path": "fibonacci2_wasm.so",
+  "port": 10004,
+  "expected-execution-us": 600,
+  "relative-deadline-us": 2000,
+  "argsize": 2,
+  "http-req-headers": [],
+  "http-req-content-type": "text/plain",
+  "http-req-size": 1024,
+  "http-resp-headers": [],
+  "http-resp-size": 1024,
+  "http-resp-content-type": "text/plain"
+},
+{
+  "active": true,
+  "name": "fibonacci3",
+  "path": "fibonacci3_wasm.so",
+  "port": 10005,
+  "expected-execution-us": 600,
+  "relative-deadline-us": 2000,
+  "argsize": 2,
+  "http-req-headers": [],
+  "http-req-content-type": "text/plain",
+  "http-req-size": 1024,
+  "http-resp-headers": [],
+  "http-resp-size": 1024,
+  "http-resp-content-type": "text/plain",
+  "tail-module": true
+}
+