The scratch space of attachment processing: a private directory tree in the
system's temporary directory (pk_agent_att/), where a user's file is copied
to be read and the pages of a scan are rendered.
Everything here is made for one user's data, so:
- the root and every directory in it are readable by the server's own user
only (mode
0700), and a directory's name is random and never reused (File.mkdir/1fails if it exists), so one run can never pick up what an earlier, killed one left behind; - the copy of a file is made inside such a directory (the destination is
ours, not a name Storage invents in
/tmp), so whatever a killed worker leaves is under one directory the supervising process removes; - a directory that nothing removed (the node was killed, a turn was stopped while it was reading a picture) is swept when its age is past the longest time a job may take — at start-up and whenever a new one is made.
A worker adopt/1s the directory its supervisor made; the directories it
makes itself are then made inside it.
Summary
Functions
Makes dir the place this process's own directories are made in.
A new, empty directory with a random name, 0700: inside the one this
process adopt/1ed, else in the root.
Copies the original of the Storage file file_uuid to a new file in dir
(readable by this user only) and returns its path.
Removes dir and what is in it.
The directory every scratch directory is made in.
Removes the scratch directories older than the longest a job may take (plus a margin). Returns how many were removed.
Runs fun with a new directory and removes it afterwards; {:error, :unreadable} where there is none to be had.
Runs fun with the path of a copy of the Storage file file_uuid, and
removes the copy afterwards. {:error, :unreadable} when it cannot be read.
Functions
@spec adopt(Path.t()) :: :ok
Makes dir the place this process's own directories are made in.
@spec create() :: {:ok, Path.t()} | {:error, :unavailable}
A new, empty directory with a random name, 0700: inside the one this
process adopt/1ed, else in the root.
Copies the original of the Storage file file_uuid to a new file in dir
(readable by this user only) and returns its path.
@spec remove(Path.t()) :: :ok
Removes dir and what is in it.
@spec root() :: Path.t()
The directory every scratch directory is made in.
@spec sweep() :: non_neg_integer()
Removes the scratch directories older than the longest a job may take (plus a margin). Returns how many were removed.
Runs fun with a new directory and removes it afterwards; {:error, :unreadable} where there is none to be had.
@spec with_file(String.t(), (Path.t() -> result)) :: result | {:error, :unreadable} when result: term()
Runs fun with the path of a copy of the Storage file file_uuid, and
removes the copy afterwards. {:error, :unreadable} when it cannot be read.