A write ahead log implementation in C++, with support for fast sequential file IO and CRC32 Checksums to preserve file integrity.
The main dependencies include cmake (>= Version 3.22) and g++/gcc with support for C++17 and onwards. For Linux systems, run
git clone https://github.com/sjay05/cwal.git
cd cwal
cmake -S . -B <build-folder>
cmake --build <build-folder>
CWAL can also be imported as a Git submodule in a CMake project with git submodule add https://github.com/sjay05/cwal.
Log entries consist of a byte_len representing the size of data in bytes, and a 4 byte CRC Checksum value (CRC_CHECKSUM).
----|-------------------|--------------------|-----------------------|-----
... | uint64_t byte_len | const string* data | uint32_t CRC_CHECKSUM | ...
| (8 bytes) | (byte_len bytes) | (4 bytes) |
----|-------------------|--------------------|-----------------------|-----
#include "walstream.h"
#include "walreader.h"
#include "walwriter.h"
#include <iostrream>
#include <vector>
int main() {
WalWriter w(FILE_FORMAT::BINARY); // support for FILE_FORMAT::TEXT also
w.open_file("foo.txt");
w.append_log(LogEntry(12, "Log Entry #1")) // <length in bytes>, <log message>
w.append_log(LogEntry(12, "Log Entry #2"))
w.append_log(LogEntry(12, "Log Entry #3"))
w.wal_fsync(); // Synchronize log file with storage device
w.rotate_log(); // Seek to ios::beg of file to overwrite.
w.close_file();
WalReader r(FILE_FORMAT::BINARY);
r.open_file("foo.txt");
vector<LogEntry> logs(3);
for (int i = 0; i < 3; i++) {
r.read_log(logs[i]);
// provided with logs[i].byte_length & logs[i].data
}
r.close_file();
}