output: add function to set context on the plugin

This change also updates the argument names to the other helper
functions to match more accurately what is being called with in
fluent-bit.

Signed-off-by: Warren Fernandes <[email protected]>

Author: Jason Keene

output/flb_output.h

@@ -20,25 +20,28 @@
 #ifndef FLBGO_OUTPUT_H
 #define FLBGO_OUTPUT_H
 
-#include <stdio.h>
-
 struct flb_api {
     char *(*output_get_property) (char *, void *);
 };
 
+struct flb_plugin_proxy_context {
+    void *remote_context;
+};
+
+/* This structure is used for initialization.
+ * It matches the one in proxy/go/go.c in fluent-bit source code.
+ */
 struct flbgo_output_plugin {
-    char *name;
+    void *_;
     struct flb_api *api;
-    void *o_ins;
-    int (*cb_init)();
-    int (*cb_flush)(void *, size_t, char *);
-    int (*cb_exit)(void *);
+    struct flb_output_instance *o_ins;
+    struct flb_plugin_proxy_context *context;
 };
 
-char *output_get_property(char *key, void *ctx)
+char *output_get_property(char *key, void *plugin)
 {
-    struct flbgo_output_plugin *plugin = ctx;
-    return plugin->api->output_get_property(key, plugin->o_ins);
+    struct flbgo_output_plugin *p = plugin;
+    return p->api->output_get_property(key, p->o_ins);
 }
 
 #endif

output/flb_plugin.h

@@ -29,8 +29,10 @@
 #define FLB_PROXY_OUTPUT_PLUGIN    2
 #define FLB_PROXY_GOLANG          11
 
-/* Structure used for registration, it match the one on flb_plugin_proxy.h */
-struct flb_plugin_proxy {
+/* This structure is used for registration.
+ * It matches the one in flb_plugin_proxy.h in fluent-bit source code.
+ */
+struct flb_plugin_proxy_def {
     int type;
     int proxy;
     int flags;

output/output.go

@@ -23,44 +23,51 @@ package output
 #include "flb_output.h"
 */
 import "C"
-import "fmt"
-import "unsafe"
+import (
+	"unsafe"
+)
 
 // Define constants matching Fluent Bit core
-const FLB_ERROR               =  C.FLB_ERROR
-const FLB_OK                  =  C.FLB_OK
-const FLB_RETRY               =  C.FLB_RETRY
+const (
+	FLB_ERROR = C.FLB_ERROR
+	FLB_OK    = C.FLB_OK
+	FLB_RETRY = C.FLB_RETRY
 
-const FLB_PROXY_OUTPUT_PLUGIN =  C.FLB_PROXY_OUTPUT_PLUGIN
-const FLB_PROXY_GOLANG        =  C.FLB_PROXY_GOLANG
+	FLB_PROXY_OUTPUT_PLUGIN = C.FLB_PROXY_OUTPUT_PLUGIN
+	FLB_PROXY_GOLANG        = C.FLB_PROXY_GOLANG
+)
 
 // Local type to define a plugin definition
-type FLBPlugin C.struct_flb_plugin_proxy
+type FLBPluginProxyDef C.struct_flb_plugin_proxy_def
 type FLBOutPlugin C.struct_flbgo_output_plugin
 
 // When the FLBPluginInit is triggered by Fluent Bit, a plugin context
 // is passed and the next step is to invoke this FLBPluginRegister() function
 // to fill the required information: type, proxy type, flags name and
 // description.
-func FLBPluginRegister(ctx unsafe.Pointer, name string, desc string) int {
-	p := (*FLBPlugin) (unsafe.Pointer(ctx))
+func FLBPluginRegister(def unsafe.Pointer, name, desc string) int {
+	p := (*FLBPluginProxyDef)(def)
 	p._type = FLB_PROXY_OUTPUT_PLUGIN
 	p.proxy = FLB_PROXY_GOLANG
 	p.flags = 0
-	p.name  = C.CString(name)
+	p.name = C.CString(name)
 	p.description = C.CString(desc)
 	return 0
 }
 
 // Release resources allocated by the plugin initialization
-func FLBPluginUnregister(ctx unsafe.Pointer) {
-	p := (*FLBPlugin) (unsafe.Pointer(ctx))
-	fmt.Printf("[flbgo] unregistering %v\n", p)
+func FLBPluginUnregister(def unsafe.Pointer) {
+	p := (*FLBPluginProxyDef)(def)
 	C.free(unsafe.Pointer(p.name))
 	C.free(unsafe.Pointer(p.description))
 }
 
-func FLBPluginConfigKey(ctx unsafe.Pointer, key string) string {
+func FLBPluginConfigKey(plugin unsafe.Pointer, key string) string {
 	_key := C.CString(key)
-	return C.GoString(C.output_get_property(_key, unsafe.Pointer(ctx)))
+	return C.GoString(C.output_get_property(_key, plugin))
+}
+
+func FLBPluginSetContext(plugin, ctx unsafe.Pointer) {
+	p := (*FLBOutPlugin)(plugin)
+	p.context.remote_context = ctx
 }