最近测试 AssetsManagerEx 的时候发现有几个无法理解的行为，想请教引擎组的大大。
1，下载资源清单文件失败后，state 不会变化到 UNCHECKED，导致不能重试 update 方法：
可以看到如果读取不到资源清单的 url 会切换状态到 UNCHECKED 并且发送 ERROR_DOWNLOAD_MANIFEST 事件：
void AssetsManagerEx::downloadManifest()
{
if (_updateState != State::PREDOWNLOAD_MANIFEST)
return;
std::string manifestUrl = _localManifest->getManifestFileUrl();
if (manifestUrl.size() > 0)
{
_updateState = State::DOWNLOADING_MANIFEST;
// Download version file asynchronously
_downloader->createDownloadFileTask(manifestUrl, _tempManifestPath, MANIFEST_ID);
}
// No manifest file found
else
{
CCLOG("AssetsManagerEx : No manifest file found, check update failed\n");
dispatchUpdateEvent(EventAssetsManagerEx::EventCode::ERROR_DOWNLOAD_MANIFEST);
_updateState = State::UNCHECKED;
}
}
但是在下载错误的回调方法中只是发送了 ERROR_DOWNLOAD_MANIFEST 事件后并没有切换状态，也没有接着发送UPDATE_FAILED 事件，其设计是下载资源清单失败后 hang 在这里吗？
void AssetsManagerEx::onError(const network::DownloadTask& task,
int errorCode,
int errorCodeInternal,
const std::string& errorStr)
{
// Skip version error occurred
if (task.identifier == VERSION_ID)
{
CCLOG("AssetsManagerEx : Fail to download version file, step skipped\n");
_updateState = State::PREDOWNLOAD_MANIFEST;
downloadManifest();
}
else if (task.identifier == MANIFEST_ID)
{
dispatchUpdateEvent(EventAssetsManagerEx::EventCode::ERROR_DOWNLOAD_MANIFEST, task.identifier, errorStr, errorCode, errorCodeInternal);
}
else
{
auto unitIt = _downloadUnits.find(task.identifier);
// Found unit and add it to failed units
if (unitIt != _downloadUnits.end())
{
_totalWaitToDownload--;
DownloadUnit unit = unitIt->second;
_failedUnits.emplace(unit.customId, unit);
}
dispatchUpdateEvent(EventAssetsManagerEx::EventCode::ERROR_UPDATING, task.identifier, errorStr, errorCode, errorCodeInternal);
}
}
2，我在 checkUpdate 后如果收到 NEW_VERSION_FOUND 后会立即调用 update 方法，在 Mac 平台上，会出现提示 More than one download file task write to same file: …，也能收到 ERROR_DOWNLOAD_MANIFEST 通知，但是到了这一步之后更新流程并没有中断，随后又会下载资源清单文件，这是我的日志：
Simulator: check update 尚未检查是否存在新版本
Simulator: get state 正在下载版本manifest文件
Simulator: get event code 更新过程的进度事件
Simulator: Processing 100.00%
Simulator: get state 检查到新版本，需要更新
Simulator: get event code 找到新版本
Simulator: New version found
Simulator: found new version, call update
Simulator: Fail to download manifest file, hot update skipped.
Simulator: update finished， null More than one download file task write to same file:/Applications/CocosCreator.app/...
Simulator: get state 正在下载资源manifest文件
Simulator: get event code 更新过程的进度事件
通过阅读源码发现是 DownloadTaskCURL 的
// include platform specific implement class
#if (CC_TARGET_PLATFORM == CC_PLATFORM_MAC)
#include "network/CCDownloader-apple.h"
#include "network/CCDownloader-curl.h"
#define DownloaderImpl DownloaderCURL
...
if (_sStoragePathSet.end() != _sStoragePathSet.find(_tempFileName))
{
// there is another task uses this storage path
_errCode = DownloadTask::ERROR_FILE_OP_FAILED;
_errCodeInternal = 0;
_errDescription = "More than one download file task write to same file:";
_errDescription.append(_tempFileName);
return false;
}
_sStoragePathSet.insert(_tempFileName);
