Rewrite LogDog log viewer app.

web/inc/rpc/client.ts

+/*
+  Copyright 2016 The LUCI Authors. All rights reserved.
+  Use of this source code is governed under the Apache License, Version 2.0
+  that can be found in the LICENSE file.
+*/
+
+import * as luci_sleep_promise from "luci-sleep-promise/promise";
+
+export namespace luci_rpc {
+
+  interface PolymerClient {
+    service: string;
+    method: string;
+    request: any;
+
+    call(): {
+      completes: Promise<any>,
+    };
+  }
+
+  export class Client {
+    transientRetry: Retry = new Retry(new RetryIterator(10, 500, null));
+    private pc: PolymerClient;
+
+    constructor(pc: any) {
+      this.pc = pc as PolymerClient;
+    }
+
+    /** Call invokes the specified service's method, returning a Promise. */
+    call<T, R>(service: string, method: string, request?: T): Promise<R> {
+      this.pc.service = service;
+      this.pc.method = method;
+      this.pc.request = request;
+
+      let transientRetry = this.transientRetry.iterator();
+      let doCall = (): Promise<R> => {
+        let callPromise: Promise<R> = this.pc.call().completes;
+        return callPromise.then( (resp: any) => {
+          return resp.response;
+        }).catch( (err: Error) => {
+          // Is this a transient error?
+          if ( isTransientError(err) ) {
+            let delay = transientRetry.next();
+            if ( delay ) {
+              console.warn(
+                `Transient error calling ${service}.${method} with params:`,
+                request, `:`, err, `; retrying after ${delay}ms.`);
+              return luci_sleep_promise.sleep(delay).then( () => {
+                return doCall();
+              });
+            }
+          }
+
+          // Non-transient, throw the error.
+          throw err;
+        });
+      };
+      return doCall();
+    }
+  }
+
+  /** gRPC Codes */
+  export enum Code {
+    OK = 0,
+    CANCELED = 1,
+    UNKNOWN = 2,
+    INVALID_ARGUMENT = 3,
+    DEADLINE_EXCEEDED = 4,
+    NOT_FOUND = 5,
+    ALREADY_EXISTS = 6,
+    PERMISSION_DENIED = 7,
+    UNAUTHENTICATED = 16,
+    RESOURCE_EXHAUSTED = 8,
+    FAILED_PRECONDITION = 9,
+    ABORTED = 10,
+    OUT_OF_RANGE = 11,
+    UNIMPLEMENTED = 12,
+    INTERNAL = 13,
+    UNAVAILABLE = 14,
+    DATA_LOSS = 15
+  }
+
+  export class GrpcError extends Error {
+    constructor(readonly code: Code, readonly description?: string) {
+      super("code = " + code + ", desc = " + description);
+    }
+
+    /**
+     * Converts the supplied Error into a GrpcError if its name is
+     * "GrpcError". This merges between the non-Typescript RPC code and this
+     * error type.
+     */
+    static convert(err: Error): GrpcError | null {
+      if ( err.name === 'GrpcError' ) {
+        let aerr = err as GrpcError;
+        return new GrpcError(aerr.code, aerr.description);
+      }
+      return null;
+    }
+
+    /** Returns true if the error is considered transient. */
+    get transient(): boolean {
+      switch ( this.code ) {
+      case Code.INTERNAL:
+      case Code.UNAVAILABLE:
+      case Code.RESOURCE_EXHAUSTED:
+        return true;
+
+      default:
+        return false;
+      }
+    }
+  }
+
+  export class HttpError extends Error {
+    constructor(readonly code: Code, readonly description?: string) {
+      super("code = " + code + ", desc = " + description);
+    }
+
+    /**
+     * Converts the supplied Error into a HttpError if its name is
+     * "HttpError". This merges between the non-Typescript RPC code and this
+     * error type.
+     */
+    static convert(err: Error): HttpError | null {
+      if ( err.name === 'HttpError' ) {
+        let aerr = err as HttpError;
+        return new HttpError(aerr.code, aerr.description);
+      }
+      return null;
+    }
+
+    /** Returns true if the error is considered transient. */
+    get transient(): boolean { return ( this.code >= 500 ); }
+  }
+
+  export function isTransientError(err: Error): boolean {
+    let grpc = GrpcError.convert(err);
+    if ( grpc ) {
+      return grpc.transient;
+    }
+
+    // Is this an HTTP Error?
+    let http = HttpError.convert(err);
+    if ( http ) {
+      return http.transient;
+    }
+
+    // Unknown error.
+    return false;
+  }
+
+  export class RetryIterator {
+    private retries: number | null;
+    private delay: number;
+    private maxDelay: number | null;
+
+    constructor(retries: number | null, delay: number,
+                maxDelay: number | null) {
+
+      this.retries = retries;
+      this.delay = delay;
+      this.maxDelay = maxDelay;
+    }
+
+    clone(): RetryIterator {
+      return new RetryIterator(this.retries, this.delay, this.maxDelay);
+    }
+
+    next(): number | null {
+      if ( this.retries !== null ) {
+        if ( this.retries <= 0 ) {
+          // No more retries remaining.
+          return null;
+        }
+        this.retries--;
+      }
+
+      let delay = this.delay;
+      this.delay *= 2;
+      if ( this.maxDelay !== null && this.delay > this.maxDelay ) {
+        this.delay = this.maxDelay;
+      }
+      return delay;
+    }
+  }
+
+  export class Retry {
+    private base: RetryIterator;
+
+    constructor(base: RetryIterator) {
+      this.base = base;
+    }
+
+    iterator(): RetryIterator {
+      return this.base.clone();
+    }
+  }
+
+}