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Feat(player): Added events for download lifecycle.
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This adds two new player events, 'downloadheadersreceived' and
'downloadfailed', to allow users to measure network performance
in greater detail.

Issue shaka-project#3533

Change-Id: I33a3bd411d815e926d4bea2184e8d3ea69e2bb49
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@theodab
theodab committed Jul 29, 2021
1 parent 38cfc23 commit 7893b77
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Showing 6 changed files with 234 additions and 63 deletions.
21 changes: 17 additions & 4 deletions externs/shaka/net.js
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Original file line number Diff line number Diff line change
Expand Up @@ -139,15 +139,17 @@ shaka.extern.Response;
* @typedef {!function(string,
* shaka.extern.Request,
* shaka.net.NetworkingEngine.RequestType,
* shaka.extern.ProgressUpdated):
* shaka.extern.ProgressUpdated,
* shaka.extern.HeadersReceived):
* !shaka.extern.IAbortableOperation.<shaka.extern.Response>}
* @description
* Defines a plugin that handles a specific scheme.
*
* The functions accepts four parameters, uri string, request, request type,
* and a progressUpdated function. The progressUpdated function can be ignored
* by plugins that do not have this information, but it will always be provided
* by NetworkingEngine.
* a progressUpdated function, and a headersReceived function. The
* progressUpdated and headersReceived functions can be ignored by plugins that
* do not have this information, but it will always be provided by
* NetworkingEngine.
*
* @exportDoc
*/
Expand All @@ -171,6 +173,17 @@ shaka.extern.SchemePlugin;
shaka.extern.ProgressUpdated;


/**
* @typedef {function(!Object.<string, string>)}
*
* @description
* A callback function to handle headers received events through networking
* engine in player.
* The first argument is the headers object of the response.
*/
shaka.extern.HeadersReceived;


/**
* Defines a filter for requests. This filter takes the request and modifies
* it before it is sent to the scheme plugin.
Expand Down
38 changes: 27 additions & 11 deletions lib/net/http_fetch_plugin.js
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Original file line number Diff line number Diff line change
Expand Up @@ -27,10 +27,12 @@ shaka.net.HttpFetchPlugin = class {
* @param {shaka.net.NetworkingEngine.RequestType} requestType
* @param {shaka.extern.ProgressUpdated} progressUpdated Called when a
* progress event happened.
* @param {shaka.extern.HeadersReceived} headersReceived Called when the
* headers for the download are received, but before the body is.
* @return {!shaka.extern.IAbortableOperation.<shaka.extern.Response>}
* @export
*/
static parse(uri, request, requestType, progressUpdated) {
static parse(uri, request, requestType, progressUpdated, headersReceived) {
const headers = new shaka.net.HttpFetchPlugin.Headers_();
shaka.util.MapUtils.asMap(request.headers).forEach((value, key) => {
headers.append(key, value);
Expand All @@ -55,7 +57,7 @@ shaka.net.HttpFetchPlugin = class {
};

const pendingRequest = shaka.net.HttpFetchPlugin.request_(
uri, requestType, init, abortStatus, progressUpdated,
uri, requestType, init, abortStatus, progressUpdated, headersReceived,
request.streamDataCallback);

/** @type {!shaka.util.AbortableOperation} */
Expand Down Expand Up @@ -92,12 +94,13 @@ shaka.net.HttpFetchPlugin = class {
* @param {!RequestInit} init
* @param {shaka.net.HttpFetchPlugin.AbortStatus} abortStatus
* @param {shaka.extern.ProgressUpdated} progressUpdated
* @param {shaka.extern.HeadersReceived} headersReceived
* @param {?function(BufferSource):!Promise} streamDataCallback
* @return {!Promise<!shaka.extern.Response>}
* @private
*/
static async request_(uri, requestType, init, abortStatus, progressUpdated,
streamDataCallback) {
headersReceived, streamDataCallback) {
const fetch = shaka.net.HttpFetchPlugin.fetch_;
const ReadableStream = shaka.net.HttpFetchPlugin.ReadableStream_;
let response;
Expand All @@ -113,6 +116,10 @@ shaka.net.HttpFetchPlugin = class {
// headers are available. The download itself isn't done until the promise
// for retrieving the data (arrayBuffer, blob, etc) has resolved.
response = await fetch(uri, init);
// At this point in the process, we have the headers of the response, but
// not the body yet.
headersReceived(shaka.net.HttpFetchPlugin.headersToGenericObject_(
response.headers));
// Getting the reader in this way allows us to observe the process of
// downloading the body, instead of just waiting for an opaque promise to
// resolve.
Expand Down Expand Up @@ -194,19 +201,28 @@ shaka.net.HttpFetchPlugin = class {
}
}

const headers = {};
/** @type {Headers} */
const responseHeaders = response.headers;
responseHeaders.forEach((value, key) => {
// Since Edge incorrectly return the header with a leading new line
// character ('\n'), we trim the header here.
headers[key.trim()] = value;
});
const headers = shaka.net.HttpFetchPlugin.headersToGenericObject_(
response.headers);

return shaka.net.HttpPluginUtils.makeResponse(
headers, arrayBuffer, response.status, uri, response.url, requestType);
}

/**
* @param {!Headers} headers
* @return {!Object.<string, string>}
* @private
*/
static headersToGenericObject_(headers) {
const headersObj = {};
headers.forEach((value, key) => {
// Since Edge incorrectly return the header with a leading new line
// character ('\n'), we trim the header here.
headersObj[key.trim()] = value;
});
return headersObj;
}

/**
* Determine if the Fetch API is supported in the browser. Note: this is
* deliberately exposed as a method to allow the client app to use the same
Expand Down
50 changes: 36 additions & 14 deletions lib/net/http_xhr_plugin.js
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Original file line number Diff line number Diff line change
Expand Up @@ -24,10 +24,12 @@ shaka.net.HttpXHRPlugin = class {
* @param {shaka.net.NetworkingEngine.RequestType} requestType
* @param {shaka.extern.ProgressUpdated} progressUpdated Called when a
* progress event happened.
* @param {shaka.extern.HeadersReceived} headersReceived Called when the
* headers for the download are received, but before the body is.
* @return {!shaka.extern.IAbortableOperation.<shaka.extern.Response>}
* @export
*/
static parse(uri, request, requestType, progressUpdated) {
static parse(uri, request, requestType, progressUpdated, headersReceived) {
const xhr = new shaka.net.HttpXHRPlugin.Xhr_();

// Last time stamp when we got a progress event.
Expand All @@ -48,23 +50,25 @@ shaka.net.HttpXHRPlugin = class {
shaka.util.Error.Code.OPERATION_ABORTED,
uri, requestType));
};
xhr.onload = (event) => {
const target = event.target;
goog.asserts.assert(target, 'XHR onload has no target!');
// Since Edge incorrectly return the header with a leading new
// line character ('\n'), we trim the header here.
const headerLines = target.getAllResponseHeaders().trim().split('\r\n');
const headers = {};
for (const header of headerLines) {
/** @type {!Array.<string>} */
const parts = header.split(': ');
headers[parts[0].toLowerCase()] = parts.slice(1).join(': ');
let calledHeadersReceived = false;
xhr.onreadystatechange = (event) => {
// See if the readyState is 2 ("HEADERS_RECEIVED").
if (xhr.readyState == 2 && !calledHeadersReceived) {
const headers = shaka.net.HttpXHRPlugin.headersToGenericObject_(xhr);
headersReceived(headers);
// Don't send out this event twice.
calledHeadersReceived = true;
}
};
xhr.onload = (event) => {
const headers = shaka.net.HttpXHRPlugin.headersToGenericObject_(xhr);
goog.asserts.assert(xhr.response instanceof ArrayBuffer,
'XHR should have a response by now!');
const xhrResponse = xhr.response;

try {
const response = shaka.net.HttpPluginUtils.makeResponse(headers,
target.response, target.status, uri, target.responseURL,
requestType);
xhrResponse, xhr.status, uri, xhr.responseURL, requestType);
resolve(response);
} catch (error) {
goog.asserts.assert(error instanceof shaka.util.Error,
Expand Down Expand Up @@ -116,6 +120,24 @@ shaka.net.HttpXHRPlugin = class {
return Promise.resolve();
});
}

/**
* @param {!XMLHttpRequest} xhr
* @return {!Object.<string, string>}
* @private
*/
static headersToGenericObject_(xhr) {
// Since Edge incorrectly return the header with a leading new
// line character ('\n'), we trim the header here.
const headerLines = xhr.getAllResponseHeaders().trim().split('\r\n');
const headers = {};
for (const header of headerLines) {
/** @type {!Array.<string>} */
const parts = header.split(': ');
headers[parts[0].toLowerCase()] = parts.slice(1).join(': ');
}
return headers;
}
};


Expand Down
99 changes: 81 additions & 18 deletions lib/net/networking_engine.js
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Original file line number Diff line number Diff line change
Expand Up @@ -48,8 +48,12 @@ shaka.net.NetworkingEngine = class extends shaka.util.FakeEventTarget {
* @param {function(number, number)=} onProgressUpdated Called when a progress
* event is triggered. Passed the duration, in milliseconds, that the
* request took, and the number of bytes transferred.
* @param {shaka.net.NetworkingEngine.OnHeadersReceived=} onHeadersReceived
* Called when the headers are received for a download.
* @param {shaka.net.NetworkingEngine.OnDownloadFailed=} onDownloadFailed
* Called when a download fails, for any reason.
*/
constructor(onProgressUpdated) {
constructor(onProgressUpdated, onHeadersReceived, onDownloadFailed) {
super();

/** @private {boolean} */
Expand All @@ -67,6 +71,12 @@ shaka.net.NetworkingEngine = class extends shaka.util.FakeEventTarget {
/** @private {?function(number, number)} */
this.onProgressUpdated_ = onProgressUpdated || null;

/** @private {?shaka.net.NetworkingEngine.OnHeadersReceived} */
this.onHeadersReceived_ = onHeadersReceived || null;

/** @private {?shaka.net.NetworkingEngine.OnDownloadFailed} */
this.onDownloadFailed_ = onDownloadFailed || null;

/** @private {boolean} */
this.forceHTTPS_ = false;
}
Expand Down Expand Up @@ -447,6 +457,8 @@ shaka.net.NetworkingEngine = class extends shaka.util.FakeEventTarget {

let aborted = false;

let headersReceivedCalled = false;

let startTimeMs;
const sendOperation = backoffOperation.chain(() => {
if (this.destroyed_) {
Expand All @@ -456,23 +468,27 @@ shaka.net.NetworkingEngine = class extends shaka.util.FakeEventTarget {
startTimeMs = Date.now();
const segment = shaka.net.NetworkingEngine.RequestType.SEGMENT;

const requestPlugin = plugin(request.uris[index],
request,
type,
// The following function is passed to plugin.
(time, bytes, numBytesRemaining) => {
if (connectionTimer) {
connectionTimer.stop();
}
if (stallTimer) {
stallTimer.tickAfter(stallTimeoutMs / 1000);
}
if (this.onProgressUpdated_ && type == segment) {
this.onProgressUpdated_(time, bytes);
gotProgress = true;
numBytesRemainingObj.setBytes(numBytesRemaining);
}
});
const progressUpdated = (time, bytes, numBytesRemaining) => {
if (connectionTimer) {
connectionTimer.stop();
}
if (stallTimer) {
stallTimer.tickAfter(stallTimeoutMs / 1000);
}
if (this.onProgressUpdated_ && type == segment) {
this.onProgressUpdated_(time, bytes);
gotProgress = true;
numBytesRemainingObj.setBytes(numBytesRemaining);
}
};
const headersReceived = (headers) => {
if (this.onHeadersReceived_) {
this.onHeadersReceived_(headers, request, type);
}
headersReceivedCalled = true;
};
const requestPlugin = plugin(
request.uris[index], request, type, progressUpdated, headersReceived);

if (!progressSupport) {
return requestPlugin;
Expand Down Expand Up @@ -511,6 +527,13 @@ shaka.net.NetworkingEngine = class extends shaka.util.FakeEventTarget {
response: response,
gotProgress: gotProgress,
};
if (!headersReceivedCalled) {
// The plugin did not call headersReceived, perhaps because it is not
// able to track that information. So, fire the event manually.
if (this.onHeadersReceived_) {
this.onHeadersReceived_(response.headers, request, type);
}
}

return responseAndGotProgress;
}, (error) => {
Expand All @@ -520,6 +543,17 @@ shaka.net.NetworkingEngine = class extends shaka.util.FakeEventTarget {
if (stallTimer) {
stallTimer.stop();
}
if (this.onDownloadFailed_) {
let shakaError = null;
let httpResponseCode = 0;
if (error instanceof shaka.util.Error) {
shakaError = error;
if (error.code == shaka.util.Error.Code.BAD_HTTP_STATUS) {
httpResponseCode = /** @type {number} */ (error.data[1]);
}
}
this.onDownloadFailed_(request, shakaError, httpResponseCode, aborted);
}
if (this.destroyed_) {
return shaka.util.AbortableOperation.aborted();
}
Expand Down Expand Up @@ -763,3 +797,32 @@ shaka.net.NetworkingEngine.schemes_ = {};
* @private
*/
shaka.net.NetworkingEngine.ResponseAndGotProgress;


/**
* @typedef {function(
* !Object.<string, string>,
* !shaka.extern.Request,
* !shaka.net.NetworkingEngine.RequestType)}
*
* @description
* A callback function that passes the shaka.extern.HeadersReceived along to
* the player, plus some extra data.
* @export
*/
shaka.net.NetworkingEngine.OnHeadersReceived;


/**
* @typedef {function(
* !shaka.extern.Request,
* ?shaka.util.Error,
* number,
* boolean)}
*
* @description
* A callback function that notifies the player when a download fails, for any
* reason (e.g. even if the download was aborted).
* @export
*/
shaka.net.NetworkingEngine.OnDownloadFailed;
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