131 lines
3.0 KiB
C++
131 lines
3.0 KiB
C++
/*
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* \brief Log session that writes messages to a file system.
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* \author Emery Hemingway
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* \date 2015-05-16
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*
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* Message writing is fire-and-forget to prevent
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* logging from becoming I/O bound.
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*/
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/*
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* Copyright (C) 2016-2017 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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#ifndef _FS_LOG__SESSION_H_
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#define _FS_LOG__SESSION_H_
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/* Genode includes */
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#include <log_session/log_session.h>
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#include <file_system_session/file_system_session.h>
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#include <base/rpc_server.h>
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#include <base/snprintf.h>
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#include <base/log.h>
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namespace Fs_log {
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enum { MAX_LABEL_LEN = 128 };
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class Session_component;
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}
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class Fs_log::Session_component : public Genode::Rpc_object<Genode::Log_session>
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{
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private:
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char _label_buf[MAX_LABEL_LEN];
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Genode::size_t const _label_len;
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File_system::Session &_fs;
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File_system::File_handle const _handle;
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public:
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Session_component(File_system::Session &fs,
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File_system::File_handle handle,
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char const *label)
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:
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_label_len(Genode::strlen(label) ? Genode::strlen(label)+3 : 0),
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_fs(fs), _handle(handle)
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{
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if (_label_len)
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Genode::snprintf(_label_buf, MAX_LABEL_LEN, "[%s] ", label);
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}
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~Session_component()
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{
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/* sync */
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File_system::Session::Tx::Source &source = *_fs.tx();
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File_system::Packet_descriptor packet = source.get_acked_packet();
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if (packet.operation() == File_system::Packet_descriptor::SYNC)
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_fs.close(packet.handle());
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packet = File_system::Packet_descriptor(
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packet, _handle, File_system::Packet_descriptor::SYNC, 0, 0);
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source.submit_packet(packet);
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}
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/*****************
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** Log session **
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*****************/
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Genode::size_t write(Log_session::String const &msg)
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{
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using namespace Genode;
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if (!msg.valid_string()) {
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Genode::error("received corrupted string");
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return 0;
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}
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size_t msg_len = strlen(msg.string());
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File_system::Session::Tx::Source &source = *_fs.tx();
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File_system::Packet_descriptor packet = source.get_acked_packet();
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if (packet.operation() == File_system::Packet_descriptor::SYNC)
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_fs.close(packet.handle());
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packet = File_system::Packet_descriptor(
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packet, _handle, File_system::Packet_descriptor::WRITE,
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msg_len, File_system::SEEK_TAIL);
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char *buf = source.packet_content(packet);
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if (_label_len) {
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memcpy(buf, _label_buf, _label_len);
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if (_label_len+msg_len > Log_session::String::MAX_SIZE) {
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packet.length(msg_len);
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source.submit_packet(packet);
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packet = File_system::Packet_descriptor(
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source.get_acked_packet(),
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_handle, File_system::Packet_descriptor::WRITE,
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msg_len, File_system::SEEK_TAIL);
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buf = source.packet_content(packet);
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} else {
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buf += _label_len;
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packet.length(_label_len+msg_len);
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}
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}
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memcpy(buf, msg.string(), msg_len);
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source.submit_packet(packet);
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return msg_len;
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}
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};
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#endif
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