This library can be used to take a snapshot of the files in a folder at a specific time, and compare the files later to get a course view of what files have been added, removed, or changed.
There are two concepts here: The "index", which is used to hash all files in a tree, and "snapshots", which save the state of the files in the index.
The index is updated every time it's accessed, re-hashing any file which has been modified since it was last accessed.
Whenever we need to see if the file has changed, we check modification time to see if the current hash is up to date. Then we can compare the current hash with the original hash.
Each line is an individual file, with the following format:
path/to/file:time:hash
Example (split into multiple lines):
engine/lib/hxcpp/hxcpp/bin/Android/libmysql5.so:
1487109988000:
ab30ecc12e7210a1625d5544af87432a22782ae7
path is the relative path from the git root to the file.
time is the modification time associated with hash.
hash is the sha-1 of the file content in its state at time.
If the file's time changes, hash is updated along with the new time.
Similar to the index file, except we only save the file name and hash:
path/to/file:hash
Snapshots may include a subset of the files in the index file.