refactor: move malloc method out of Wasm VM (#91)

Author: spacewander

config

@@ -20,6 +20,7 @@ ngx_module_srcs=" \
     $ngx_addon_dir/src/http/ngx_http_wasm_call.c \
     $ngx_addon_dir/src/http/ngx_http_wasm_state.c \
     $ngx_addon_dir/src/proxy_wasm/proxy_wasm_map.c \
+    $ngx_addon_dir/src/proxy_wasm/proxy_wasm_memory.c \
     $ngx_addon_dir/src/vm/wasmtime.c \
     $ngx_addon_dir/src/vm/vm.c \
 "

src/http/ngx_http_wasm_api.c

@@ -23,6 +23,7 @@
 #include "ngx_http_wasm_call.h"
 #include "ngx_http_wasm_ctx.h"
 #include "proxy_wasm/proxy_wasm_map.h"
+#include "proxy_wasm/proxy_wasm_memory.h"
 
 
 typedef struct {
@@ -201,7 +202,7 @@ ngx_http_wasm_copy_to_wasm(ngx_log_t *log, const u_char *data, int32_t len,
         return PROXY_RESULT_OK;
     }
 
-    buf_addr = ngx_wasm_vm.malloc(log, len);
+    buf_addr = proxy_wasm_memory_alloc(log, len);
     if (buf_addr == 0) {
         ngx_log_error(NGX_LOG_ERR, log, 0, "no memory");
         return PROXY_RESULT_INTERNAL_FAILURE;
@@ -233,7 +234,7 @@ ngx_http_wasm_get_buf_to_write(ngx_log_t *log, int32_t len,
     int32_t        *p;
     u_char         *buf;
 
-    buf_addr = ngx_wasm_vm.malloc(log, len);
+    buf_addr = proxy_wasm_memory_alloc(log, len);
     if (buf_addr == 0) {
         ngx_log_error(NGX_LOG_ERR, log, 0, "no memory");
         return NULL;

src/proxy_wasm/proxy_wasm_memory.c

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2022 Shenzhen ZhiLiu Technology Co., Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+#include "vm/vm.h"
+#include "proxy_wasm_memory.h"
+
+
+static ngx_str_t proxy_on_memory_allocate = ngx_string("proxy_on_memory_allocate");
+static ngx_str_t exported_malloc = ngx_string("malloc");
+
+
+int32_t proxy_wasm_memory_alloc(ngx_log_t *log, int32_t size)
+{
+    int32_t         addr;
+
+    addr = ngx_wasm_vm.call(NULL, &proxy_on_memory_allocate, true, NGX_WASM_PARAM_I32, size);
+    if (addr == 0) {
+        addr = ngx_wasm_vm.call(NULL, &exported_malloc, true, NGX_WASM_PARAM_I32, size);
+    }
+
+    if (addr == 0) {
+        ngx_log_error(NGX_LOG_ERR, log, 0, "failed to malloc");
+    }
+
+    return addr;
+}

src/proxy_wasm/proxy_wasm_memory.h

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2022 Shenzhen ZhiLiu Technology Co., Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+#ifndef PROXY_WASM_MEMORY_H
+#define PROXY_WASM_MEMORY_H
+#include <ngx_core.h>
+
+
+/*
+ * malloc allocates memory in WASM, and then return the address of the allocated
+ * memory.
+ */
+int32_t proxy_wasm_memory_alloc(ngx_log_t *log, int32_t size);
+
+
+#endif // PROXY_WASM_MEMORY_H

src/vm/vm.h

@@ -44,11 +44,6 @@ typedef struct {
      * It returns NULL if addr + size is out of bound.
      */
     u_char          *(*get_memory)(ngx_log_t *log, int32_t addr, int32_t size);
-    /*
-     * malloc allocates memory in WASM, and then return the address of the allocated
-     * memory.
-     */
-    int32_t          (*malloc)(ngx_log_t *log, int32_t size);
 
     /*
      * call run a function exported from the plugin.

src/vm/wasmtime.c

@@ -244,6 +244,12 @@ ngx_wasm_wasmtime_call(void *data, ngx_str_t *name, bool has_result, int param_t
 
     ngx_log_debug1(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0, "wasmtime call function %V", name);
 
+    if (plugin == NULL) {
+        plugin = cur_plugin;
+    } else {
+        cur_plugin = plugin;
+    }
+
     found = wasmtime_instance_export_get(plugin->context, &plugin->instance,
                                          (const char *) name->data, name->len, &func);
     if (!found) {
@@ -252,8 +258,6 @@ ngx_wasm_wasmtime_call(void *data, ngx_str_t *name, bool has_result, int param_t
         return NGX_OK;
     }
 
-    cur_plugin = plugin;
-
     va_start(args, param_type);
 
     switch (param_type) {
@@ -360,48 +364,13 @@ ngx_wasm_wasmtime_get_memory(ngx_log_t *log, int32_t addr, int32_t size)
 }
 
 
-int32_t
-ngx_wasm_wasmtime_malloc(ngx_log_t *log, int32_t size)
-{
-    wasmtime_extern_t           func;
-    wasm_trap_t                *trap = NULL;
-    wasmtime_error_t           *error;
-    wasmtime_val_t              params[1];
-    wasmtime_val_t              results[1];
-    bool                        found;
-
-    found = wasmtime_instance_export_get(cur_plugin->context, &cur_plugin->instance,
-                                         "proxy_on_memory_allocate", 24, &func);
-    if (!found) {
-        found = wasmtime_instance_export_get(cur_plugin->context, &cur_plugin->instance,
-                                             "malloc", 6, &func);
-        if (!found) {
-            ngx_log_error(NGX_LOG_ERR, log, 0, "can't find malloc in the WASM plugin");
-            return 0;
-        }
-    }
-
-    params[0].kind = WASMTIME_I32;
-    params[0].of.i32 = size;
-
-    error = wasmtime_func_call(cur_plugin->context, &func.of.func, params, 1, results, 1, &trap);
-    if (error != NULL || trap != NULL) {
-        ngx_wasm_wasmtime_report_error(log, "failed to malloc: ", error, trap);
-        return 0;
-    }
-
-    return results[0].of.i64;
-}
-
-
 ngx_wasm_vm_t ngx_wasm_vm = {
     &vm_name,
     ngx_wasm_wasmtime_init,
     ngx_wasm_wasmtime_cleanup,
     ngx_wasm_wasmtime_load,
     ngx_wasm_wasmtime_unload,
     ngx_wasm_wasmtime_get_memory,
-    ngx_wasm_wasmtime_malloc,
     ngx_wasm_wasmtime_call,
     ngx_wasm_wasmtime_has,
 };