Revert of Rewrite LogDog log viewer app.

web/inc/logdog-stream-view/logdog-stream-fetcher.html

+<!--
+  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.
+  -->
+
+<link rel="import" href="../bower_components/polymer/polymer.html">
+<link rel="import" href="../bower_components/promise-polyfill/promise-polyfill-lite.html">
+
+<link rel="import" href="../luci-sleep-promise/luci-sleep-promise.html">
+
+<script>
+  "use strict";
+
+  function LogDogFetcher(client, stream) {
+    this.client = client;
+    this.stream = stream;
+
+    // Fetching parameters, will be updated as logs are fetched.
+    this.sleepTimeSecs = 5;
+    this.byteCount = null;
+    this.logCount = null;
+    this.reset();
+  }
+
+  LogDogFetcher.prototype.reset = function() {
+    this.nextIndex = 0;
+    this.finished = false;
+    this.desc = null;
+    this.state = null;
+
+    this._current = null;
+    this._nextLogsPromise = null;
+  };
+
+  /**
+   * Returns the log stream's terminal index.
+   *
+   * If no terminal index is known, or if the log stream is still streaming,
+   * this will return -1.
+   */
+  LogDogFetcher.prototype.terminalIndex = function() {
+    return (this.state) ? (this.state.terminalIndex) : (-1);
+  };
+
+  /**
+   * Returns a Promise that resolves to the next block of logs in the stream.
+   *
+   * If there are no more logs in the stream (finished), the returned Promise
+   * will already be resolved and will contain a null log.
+   *
+   * @return {Promise[Object]} A Promise that will resolve to the next block
+   *     of logs in the stream.
+   */
+  LogDogFetcher.prototype.next = function() {
+    // If we don't have an in-progress fetch, start a new one.
+    if (this._nextLogsPromise === null) {
+      this._nextLogsPromise = this._fetchNextBatch().
+          then(function(result) {
+            var entries = result.entries;
+            if (entries && entries.length) {
+              var lastIndex = entries[entries.length-1].streamIndex;
+              this.nextIndex = (lastIndex + 1);
+
+              var tidx = this.terminalIndex();
+              if (tidx >= 0 && tidx < this.nextIndex) {
+                // We have punted the full log stream. Mark finished.
+                this.finished = true;
+              }
+            }
+
+            this._nextLogsPromise = null;
+            return result;
+          }.bind(this)).catch(function(error) {
+            this._nextLogsPromise = null;
+            throw error;
+          }.bind(this));
+    }
+    return this._nextLogsPromise;
+  },
+
+  /** Creates and returns a Promise for the next batch of logs. */
+  LogDogFetcher.prototype._fetchNextBatch = function() {
+    // If we're already finished, return the terminal result.
+    if (this.finished) {
+      return this._resolvedLogs(null);
+    }
+
+    // Fetch and return the next batch of logs.
+    return this._scheduleAsyncGet().then(function(resp) {
+      // Update our state/desc.
+      if (resp.state) {
+        this.state = resp.state;
+      }
+      if (resp.desc) {
+        this.desc = resp.desc;
+      }
+
+      var logs = resp.logs;
+      if (! (logs && logs.length)) {
+        // No logs were loaded this round. Sleep for a bit then try again.
+        // (Streaming case).
+        console.log("No logs for", this.stream, "; sleeping...");
+        return new LuciSleepPromise(this.sleepTimeSecs * 1000).
+          then(function() {
+            return this._fetchNextBatch();
+          }.bind(this));
+      }
+
+      return this._resolvedLogs(logs);
+    }.bind(this));
+  };
+
+  /** Generates a structured Promise for a given block of log entries. */
+  LogDogFetcher.prototype._resolvedLogs = function(punt) {
+    return Promise.resolve({
+      desc: this.desc,
+      state: this.state,
+      entries: punt,
+    });
+  };
+
+  /** Schedules the next asynchronous fetch. */
+  LogDogFetcher.prototype._scheduleAsyncGet = function() {
+    this.client.service = "logdog.Logs";
+    this.client.method = "Get";
+    this.client.request = {
+      project: this.stream.project,
+      path: this.stream.path,
+      state: (!this.state || this.terminalIndex() < 0),
+      index: this.nextIndex,
+    };
+
+    if (this.byteCount !== null) {
+      this.client.request.byteCount = this.byteCount;
+    }
+    if (this.logCount !== null) {
+      this.client.request.logCount = this.logCount;
+    }
+
+    return this.client.call().completes.then(function(resp) {
+      resp = resp.response;
+
+      // Normalize the resulting logs.
+      //
+      // JSONPB timestamps are in the form of RFC3339 strings.
+      if (resp.desc) {
+        patchDescriptor(resp.desc);
+      }
+      if (resp.state) {
+        patchState(resp.state);
+      }
+      if (resp.logs) {
+        resp.logs.forEach(function(le) {
+          patchLogEntry(le, resp.desc);
+        });
+      }
+
+      return resp;
+    }, function(error) {
+      throw LogDogError.wrapGrpc(error);
+    });
+  };
+</script>