daemon: adding write retry loop; retry for EINTR, EAGAIN, EWOULDBLOCK (9ab18557) · Commits · hpc / gekkofs

include/daemon/backend/data/chunk_storage.hpp

+1 −1

Original line number	Diff line number	Diff line
		@@ -63,7 +63,7 @@ public:
		void destroy_chunk_space(const std::string& file_path) const;

		ssize_t
		write_chunk(const std::string& file_path, gkfs::rpc::chnk_id_t chunk_id, const char* buff, size_t size,
		write_chunk(const std::string& file_path, gkfs::rpc::chnk_id_t chunk_id, const char* buf, size_t size,
		off64_t offset) const;

		ssize_t read_chunk(const std::string& file_path, gkfs::rpc::chnk_id_t chunk_id, char* buf, size_t size,

src/daemon/backend/data/chunk_storage.cpp

+36 −18

Original line number	Diff line number	Diff line
		@@ -117,14 +117,14 @@ void ChunkStorage::destroy_chunk_space(const string& file_path) const {
		*
		* @param file_path
		* @param chunk_id
		* @param buff
		* @param buf
		* @param size
		* @param offset
		* @param eventual
		* @throws ChunkStorageException (caller will handle eventual signalling)
		*/
		ssize_t
		ChunkStorage::write_chunk(const string& file_path, gkfs::rpc::chnk_id_t chunk_id, const char* buff, size_t size,
		ChunkStorage::write_chunk(const string& file_path, gkfs::rpc::chnk_id_t chunk_id, const char* buf, size_t size,
		off64_t offset) const {

		assert((offset + size) <= chunksize_);
		@@ -140,14 +140,29 @@ ChunkStorage::write_chunk(const string& file_path, gkfs::rpc::chnk_id_t chunk_id
		throw ChunkStorageException(errno, err_str);
		}

		auto wrote = pwrite(fh.native(), buff, size, offset);
		size_t wrote_total{};
		ssize_t wrote{};

		do {
		wrote = pwrite(fh.native(),
		buf + wrote_total,
		size - wrote_total,
		offset + wrote_total);

		if (wrote < 0) {
		auto err_str = fmt::format("{}() Failed to write chunk file. File: '{}', size: '{}', offset: '{}', Error: '{}'",
		// retry if a signal or anything else has interrupted the read system call
		if (errno == EINTR \|\| errno == EAGAIN \|\| errno == EWOULDBLOCK)
		continue;
		auto err_str = fmt::format(
		"{}() Failed to write chunk file. File: '{}', size: '{}', offset: '{}', Error: '{}'",
		__func__, chunk_path, size, offset, ::strerror(errno));
		throw ChunkStorageException(errno, err_str);
		}
		wrote_total += wrote;
		} while (wrote_total != size);

		// file is closed via the file handle's destructor.
		return wrote;
		return wrote_total;
		}

		/**
		@@ -175,14 +190,14 @@ ChunkStorage::read_chunk(const string& file_path, gkfs::rpc::chnk_id_t chunk_id,
		chunk_path, ::strerror(errno));
		throw ChunkStorageException(errno, err_str);
		}
		size_t tot_read = 0;
		size_t read_total = 0;
		ssize_t read = 0;

		do {
		read = pread64(fh.native(),
		buf + tot_read,
		size - tot_read,
		offset + tot_read);
		buf + read_total,
		size - read_total,
		offset + read_total);
		if (read == 0) {
		/*
		* A value of zero indicates end-of-file (except if the value of the size argument is also zero).
		@@ -194,23 +209,26 @@ ChunkStorage::read_chunk(const string& file_path, gkfs::rpc::chnk_id_t chunk_id,
		}

		if (read < 0) {
		// retry if a signal or anything else has interrupted the read system call
		if (errno == EINTR \|\| errno == EAGAIN \|\| errno == EWOULDBLOCK)
		continue;
		auto err_str = fmt::format("Failed to read chunk file. File: '{}', size: '{}', offset: '{}', Error: '{}'",
		chunk_path, size, offset, ::strerror(errno));
		throw ChunkStorageException(errno, err_str);
		}

		#ifndef NDEBUG
		if (tot_read + read < size) {
		if (read_total + read < size) {
		log_->debug("Read less bytes than requested: '{}'/{}. Total read was '{}'. This is not an error!", read,
		size - tot_read, size);
		size - read_total, size);
		}
		#endif
		assert(read > 0);
		tot_read += read;
		} while (tot_read != size);
		read_total += read;
		} while (read_total != size);

		// file is closed via the file handle's destructor.
		return tot_read;
		return read_total;
		}

		/**