From 53247d6b116905e7233b1efd6c14845e20d27442 Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Wed, 10 Jul 2019 23:12:17 +0200 Subject: [PATCH] Resume NAR downloads This is a much simpler fix to the 'error 9 while decompressing xz file' problem than 78fa47a7f08a4cb6ee7061bf0bd86a40e1d6dc91. We just do a ranged HTTP request starting after the data that we previously wrote into the sink. Fixes #2952, #379. --- src/libstore/download.cc | 35 ++++++++++++++++++++++++++++------- 1 file changed, 28 insertions(+), 7 deletions(-) diff --git a/src/libstore/download.cc b/src/libstore/download.cc index 195eccc2a12..91087eebcfc 100644 --- a/src/libstore/download.cc +++ b/src/libstore/download.cc @@ -71,6 +71,10 @@ struct CurlDownloader : public Downloader std::string encoding; + bool acceptRanges = false; + + curl_off_t writtenToSink = 0; + DownloadItem(CurlDownloader & downloader, const DownloadRequest & request, Callback callback) @@ -81,9 +85,10 @@ struct CurlDownloader : public Downloader {request.uri}, request.parentAct) , callback(callback) , finalSink([this](const unsigned char * data, size_t len) { - if (this->request.dataCallback) + if (this->request.dataCallback) { + writtenToSink += len; this->request.dataCallback((char *) data, len); - else + } else this->result.data->append((char *) data, len); }) { @@ -161,6 +166,7 @@ struct CurlDownloader : public Downloader status = ss.size() >= 2 ? ss[1] : ""; result.data = std::make_shared(); result.bodySize = 0; + acceptRanges = false; encoding = ""; } else { auto i = line.find(':'); @@ -178,7 +184,9 @@ struct CurlDownloader : public Downloader return 0; } } else if (name == "content-encoding") - encoding = trim(string(line, i + 1));; + encoding = trim(string(line, i + 1)); + else if (name == "accept-ranges" && toLower(trim(std::string(line, i + 1))) == "bytes") + acceptRanges = true; } } return realSize; @@ -296,6 +304,9 @@ struct CurlDownloader : public Downloader curl_easy_setopt(req, CURLOPT_NETRC_FILE, settings.netrcFile.get().c_str()); curl_easy_setopt(req, CURLOPT_NETRC, CURL_NETRC_OPTIONAL); + if (writtenToSink) + curl_easy_setopt(req, CURLOPT_RESUME_FROM_LARGE, writtenToSink); + result.data = std::make_shared(); result.bodySize = 0; } @@ -330,7 +341,7 @@ struct CurlDownloader : public Downloader failEx(writeException); else if (code == CURLE_OK && - (httpStatus == 200 || httpStatus == 201 || httpStatus == 204 || httpStatus == 304 || httpStatus == 226 /* FTP */ || httpStatus == 0 /* other protocol */)) + (httpStatus == 200 || httpStatus == 201 || httpStatus == 204 || httpStatus == 206 || httpStatus == 304 || httpStatus == 226 /* FTP */ || httpStatus == 0 /* other protocol */)) { result.cached = httpStatus == 304; done = true; @@ -403,10 +414,20 @@ struct CurlDownloader : public Downloader request.verb(), request.uri, curl_easy_strerror(code), code)); /* If this is a transient error, then maybe retry the - download after a while. */ - if (err == Transient && attempt < request.tries) { + download after a while. If we're writing to a + sink, we can only retry if the server supports + ranged requests. */ + if (err == Transient + && attempt < request.tries + && (!this->request.dataCallback + || writtenToSink == 0 + || (acceptRanges && encoding.empty()))) + { int ms = request.baseRetryTimeMs * std::pow(2.0f, attempt - 1 + std::uniform_real_distribution<>(0.0, 0.5)(downloader.mt19937)); - warn("%s; retrying in %d ms", exc.what(), ms); + if (writtenToSink) + warn("%s; retrying from offset %d in %d ms", exc.what(), writtenToSink, ms); + else + warn("%s; retrying in %d ms", exc.what(), ms); embargo = std::chrono::steady_clock::now() + std::chrono::milliseconds(ms); downloader.enqueueItem(shared_from_this()); }