Summary

Cache the results of is_exe_in_path.

Review Request #11823 — Created Sept. 27, 2021 and submitted Sept. 28, 2021, 5:23 p.m.

Information

Owner

chipx86

Repository

RBTools

Branch

master

Bugs

Depends On

Reviewers

Groups

rbtools

People

Description

is_exe_in_path() may be called multiple times with the same executable

name, particularly when running from unit tests. Since an executable is

unlikely to appear or disappear within the lifetime of a process run in

a way that impacts RBTools, it's not worth re-scanning the whole path

every time we need to know if an executable is available.
This change adds caching behavior to is_exe_in_path(). Now, a repeated

call with the same executable name (with or without a .exe file

extension) will return the prior cached result.

Testing Done

All unit tests pass.

Commits

Summary	ID
Cache the results of is_eze_in_path. `is_exe_in_path()` may be called multiple times with the same executable name, particularly when running from unit tests. Since an executable is unlikely to appear or disappear within the lifetime of a process run in a way that impacts RBTools, it's not worth re-scanning the whole path every time we need to know if an executable is available. This change adds caching behavior to `is_exe_in_path()`. Now, a repeated call with the same executable name (with or without a `.exe` file extension) will return the prior cached result.	f90f6317d91f94af75fe1b11001d58d03b6986b9

Summary

Cache the results of is_eze_in_path.

`is_exe_in_path()` may be called multiple times with the same executable name, particularly when running from unit tests. Since an executable is unlikely to appear or disappear within the lifetime of a process run in a way that impacts RBTools, it's not worth re-scanning the whole path every time we need to know if an executable is available. This change adds caching behavior to `is_exe_in_path()`. Now, a repeated call with the same executable name (with or without a `.exe` file extension) will return the prior cached result.

f90f6317d91f94af75fe1b11001d58d03b6986b9

Issues

Description	From	Last Updated
Might be a little simpler as: if name not in _exe_in_path_cache: ... _exe_in_path_cache[name] = found return _exe_in_path_cache[name]	david	Sept. 27, 2021, 10:02 p.m.

flake8 passed.

JSHint passed.

rbtools/utils/filesystem.py (Diff revision 1)

The issue has been dropped. Show all issues

Might be a little simpler as:

if name not in _exe_in_path_cache:
    ...
    _exe_in_path_cache[name] = found

return _exe_in_path_cache[name]

chipx86 Sept. 27, 2021, 2:28 p.m.

This is a pretty common pattern when using a dictionary as a cache. You avoid the repeated lookups in the dictionary by assuming the key is present, and then only writing to the dictionary if not. Saves a dictionary lookup. This code isn't a bottleneck, but the pattern's a good one.

Another option is I could switch to @lru_cache, but it's only in Python 3 (without depending on a backport for 2).

david Sept. 27, 2021, 10:02 p.m.
```
OK, sure.
```

Ship it!

```
Ship It!
```

Ship it!

```
Ship It!
```

Status:: Completed
Change Summary:: Pushed to master (dc70d35)