[libcxx-commits] [libcxx] [libc++][lit] Atomically update the persistent cache (PR #66538)

[Alexander Richardson via libcxx-commits]

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@@ -69,8 +69,12 @@ def f(config, *args, **kwargs):
             if cacheKey not in cache:
                 cache[cacheKey] = function(config, *args, **kwargs)
                 # Update the persistent cache so it knows about the new key
-                with open(persistentCache, "wb") as cacheFile:
+                # We write to a temporary file and rename the result to ensure
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arichardson wrote:

Hmm that's a good point, in my limited testing this was enough to avoid the race, but really it should be a per-shard suffix. Will update to use the PID.

https://github.com/llvm/llvm-project/pull/66538