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BaseCrawlFacade.cs
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BaseCrawlFacade.cs
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namespace tbm.Crawler.Tieba.Crawl.Facade
{
public abstract class BaseCrawlFacade<TPost, TResponse, TPostProtoBuf, TCrawler> : IDisposable
where TPost : class, IPost where TCrawler : BaseCrawler<TResponse, TPostProtoBuf>
where TResponse : IMessage<TResponse> where TPostProtoBuf : IMessage<TPostProtoBuf>
{
private readonly ILogger<BaseCrawlFacade<TPost, TResponse, TPostProtoBuf, TCrawler>> _logger;
private readonly TbmDbContext.New _dbContextFactory;
private readonly BaseCrawler<TResponse, TPostProtoBuf> _crawler;
private readonly BaseParser<TPost, TPostProtoBuf> _parser;
private readonly BaseSaver<TPost> _saver;
protected UserParserAndSaver Users { get; }
private readonly ClientRequesterTcs _requesterTcs;
private readonly CrawlerLocks _locks; // singleton for every derived class
private readonly CrawlerLocks.LockId _lockId;
private ExceptionHandler _exceptionHandler = _ => { };
public delegate void ExceptionHandler(Exception ex);
protected uint Fid { get; }
protected ConcurrentDictionary<ulong, TPost> ParsedPosts { get; } = new();
private readonly HashSet<Page> _lockingPages = new();
protected BaseCrawlFacade(
ILogger<BaseCrawlFacade<TPost, TResponse, TPostProtoBuf, TCrawler>> logger,
TbmDbContext.New dbContextFactory,
BaseCrawler<TResponse, TPostProtoBuf> crawler,
BaseParser<TPost, TPostProtoBuf> parser,
Func<ConcurrentDictionary<PostId, TPost>, BaseSaver<TPost>> saverFactory,
UserParserAndSaver users,
ClientRequesterTcs requesterTcs,
(CrawlerLocks, CrawlerLocks.LockId) lockAndId,
Fid fid)
{
_logger = logger;
_dbContextFactory = dbContextFactory;
_crawler = crawler;
_parser = parser;
_saver = saverFactory(ParsedPosts);
Users = users;
_requesterTcs = requesterTcs;
(_locks, _lockId) = lockAndId;
Fid = fid;
}
~BaseCrawlFacade() => Dispose();
public void Dispose()
{
GC.SuppressFinalize(this);
_locks.ReleaseRange(_lockId, _lockingPages);
}
protected virtual void BeforeCommitSaveHook(TbmDbContext db) { }
protected virtual void PostCommitSaveHook(SaverChangeSet<TPost> savedPosts, CancellationToken stoppingToken = default) { }
public SaverChangeSet<TPost>? SaveCrawled(CancellationToken stoppingToken = default)
{
var db = _dbContextFactory(Fid);
using var transaction = db.Database.BeginTransaction(IsolationLevel.ReadCommitted);
var savedPosts = ParsedPosts.IsEmpty ? null : _saver.SavePosts(db);
Users.SaveUsers(db, _saver.PostType, _saver.TiebaUserFieldChangeIgnorance);
BeforeCommitSaveHook(db);
try
{
_ = db.SaveChanges();
transaction.Commit();
if (savedPosts != null) PostCommitSaveHook(savedPosts, stoppingToken);
}
finally
{
_saver.OnPostSaveEvent();
Users.PostSaveHook();
}
return savedPosts;
}
public async Task<BaseCrawlFacade<TPost, TResponse, TPostProtoBuf, TCrawler>>
CrawlPageRange(Page startPage, Page endPage = Page.MaxValue, CancellationToken stoppingToken = default)
{ // cancel when startPage is already locked
if (_lockingPages.Any()) throw new InvalidOperationException(
"CrawlPageRange() can only be called once, a instance of BaseCrawlFacade shouldn't be reuse for other crawls.");
var acquiredLocks = _locks.AcquireRange(_lockId, new[] {startPage}).ToHashSet();
if (!acquiredLocks.Any()) _logger.LogInformation(
"Cannot crawl any page within the range [{}-{}] for lock type {}, id {} since they've already been locked",
startPage, endPage, _locks.LockType, _lockId);
_lockingPages.UnionWith(acquiredLocks);
var isStartPageCrawlFailed = await LogException(async () =>
{
var startPageResponse = await _crawler.CrawlSinglePage(startPage, stoppingToken);
startPageResponse.ForEach(ValidateThenParse);
var maxPage = startPageResponse
.Select(r => _crawler.GetResponsePage(r.Result))
.Max(p => (Page?)p?.TotalPage);
endPage = Math.Min(endPage, maxPage ?? Page.MaxValue);
}, startPage, 0, stoppingToken);
if (!isStartPageCrawlFailed)
{
var pagesAfterStart = Enumerable.Range(
(int)(startPage + 1),
(int)(endPage - startPage)).ToList();
if (pagesAfterStart.Any())
await CrawlPages(pagesAfterStart.Select(i => (Page)i), stoppingToken: stoppingToken);
}
return this;
}
private Task CrawlPages(IEnumerable<Page> pages,
Func<Page, FailureCount>? previousFailureCountSelector = null, CancellationToken stoppingToken = default)
{
var pagesList = pages.ToList();
var acquiredLocks = _locks.AcquireRange(_lockId, pagesList).ToList();
if (!acquiredLocks.Any())
{
var pagesText = Enumerable.Range((int)pagesList[0], (int)pagesList[^1])
.Select(i => (Page)i).SequenceEqual(pagesList)
? $"within the range [{pagesList[0]}-{pagesList[^1]}]"
: JsonSerializer.Serialize(pagesList);
_logger.LogInformation("Cannot crawl any page within {} for lock type {}, id {} since they've already been locked",
pagesText, _locks.LockType, _lockId);
}
_lockingPages.UnionWith(acquiredLocks);
return Task.WhenAll(acquiredLocks.Shuffle()
.Select(page => LogException(
async () => (await _crawler.CrawlSinglePage(page, stoppingToken)).ForEach(ValidateThenParse),
page, previousFailureCountSelector?.Invoke(page) ?? 0, stoppingToken)));
}
public async Task<SaverChangeSet<TPost>?> RetryThenSave(IEnumerable<Page> pages,
Func<Page, FailureCount> failureCountSelector, CancellationToken stoppingToken = default)
{
if (_lockingPages.Any()) throw new InvalidOperationException(
"RetryPages() can only be called once, a instance of BaseCrawlFacade shouldn't be reuse for other crawls.");
await CrawlPages(pages, failureCountSelector, stoppingToken);
return SaveCrawled(stoppingToken);
}
private async Task<bool> LogException(Func<Task> payload, Page page,
FailureCount previousFailureCount, CancellationToken stoppingToken)
{
try
{
await payload();
return false;
}
catch (OperationCanceledException e) when (e.CancellationToken == stoppingToken)
{
throw;
}
catch (Exception e)
{
e.Data["page"] = page;
e.Data["fid"] = Fid;
e = _crawler.FillExceptionData(e).ExtractInnerExceptionsData();
if (e is TiebaException te)
{
if (!te.ShouldSilent)
_logger.LogWarning("TiebaException: {} {}",
string.Join(' ', e.GetInnerExceptions().Select(ex => ex.Message)),
Helper.UnescapedJsonSerialize(e.Data));
}
else _logger.LogError(e, "Exception");
if (e is not TiebaException {ShouldRetry: false})
{
_locks.AcquireFailed(_lockId, page, (FailureCount)(previousFailureCount + 1));
_requesterTcs.Decrease();
}
try
{
_exceptionHandler(e);
}
catch (Exception ex)
{
_logger.LogError(ex, "Exception");
return true;
}
return true;
}
}
public BaseCrawlFacade<TPost, TResponse, TPostProtoBuf, TCrawler> AddExceptionHandler(ExceptionHandler handler)
{
_exceptionHandler += handler;
return this;
}
private void ValidateThenParse(BaseCrawler<TResponse, TPostProtoBuf>.Response responseTuple)
{
var (response, flag) = responseTuple;
var posts = _crawler.GetValidPosts(response, flag);
try
{
_parser.ParsePosts(flag, posts, ParsedPosts, out var postsEmbeddedUsers);
if (flag != CrawlRequestFlag.None) return;
if (!postsEmbeddedUsers.Any() && posts.Any()) ThrowIfEmptyUsersEmbedInPosts();
if (postsEmbeddedUsers.Any()) Users.ParseUsers(postsEmbeddedUsers);
}
finally
{
PostParseHook(response, flag);
}
}
protected virtual void ThrowIfEmptyUsersEmbedInPosts() { }
protected virtual void PostParseHook(TResponse response, CrawlRequestFlag flag) { }
}
}