fantiq commented on issue #15291:
URL: https://github.com/apache/dubbo/issues/15291#issuecomment-3134767474
## Cause
When `dubbo-compiler` generate java files from a proto file, it uses the two
variables `originMethodName` and `methodName`.
The value of the variable `originMethodName` is the name of the rpc method,
the value of the variable `methodName` will lowercase the first letter of the
rpc method name.
`methodName` is used to fill in the method name of the generated interface
class.
`originMethodName` is used to fill the value of the `methodName` parameter
when instantiating the StubMethodDescriptor object in the generated code.
when the triple protocol registers the rest router, it will traverse the
interface method and find the StubMethodDescriptor object by the method name.
if the first letter of the RPC method name is capitalized, the
StubMethodDescriptor object will not be found here, causing the routing
registration to fail.
e.g.
```
service GreeterService {
rpc SayHello(HelloRequest) returns (HelloReply);
}
```
as defined above, when generate the code, the value of variable
`originMethodName` whill be `SayHello`,
the value of variable `methodName` whill be `sayHello`.
## Solution
### 1. introduce the option in proto
we can define an option like this:
```
extend google.protobuf.MethodOptions {
string java_method_name = 1001;
}
```
use like this:
```
import "org/apache/dubbo/compiler/options.proto";
service GreeterService {
rpc SayHello(HelloRequest) returns (HelloReply) {
option (java_method_name) = "sayHello";
}
}
```
If the developer uses `java_method_name` to specify the method name, the
values of the template variables `originMethodName` and `methodName` when
generating code will use the same values specified by `java_method_name`.
### 2. associate the value of the `methodName` variable with the
StubMethodDescriptor object
When i learned about oxsean's work on da8fd19, perhaps we can consider
storing the value of the variable `methodName` in the `ConcurrentMap<String,
Object> attributeMap` property of `StubMethodDescriptor` in the generated code.
e.g.
if the rpc defined like this:
```
service GreeterService {
rpc SayHello(HelloRequest) returns (HelloReply);
}
```
The code generated by `dubbo-compiler` is as follows:
```java
private static final StubMethodDescriptor sayHelloMethod = new
StubMethodDescriptor("SayHello",
org.apache.dubbo.demo.hello.HelloRequest.class,
org.apache.dubbo.demo.hello.HelloReply.class, MethodDescriptor.RpcType.UNARY,
obj -> ((Message) obj).toByteArray(), obj -> ((Message) obj).toByteArray(),
org.apache.dubbo.demo.hello.HelloRequest::parseFrom,
org.apache.dubbo.demo.hello.HelloReply::parseFrom);
static {
sayHelloMethod.addAttribute("methodName", "sayHello");
serviceDescriptor.addMethod(sayHelloMethod);
}
```
When calling the `addMethod(MethodDescriptor)` method, prioritize the method
name on the `attributeMap`. and it will continue based on da8fd19 .
## Trade off
solution 1 only requires modifying the `dubbo-compiler`, but requires manual
settings by the developer.
solution 2 involves more changes, but users are unaware of them.
any suggestions? @oxsean @paxxie2 @zrlw
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