Module cache 

Shared binary cache for PostgreSQL downloads.

This module provides caching infrastructure to avoid repeated downloads of PostgreSQL binaries when multiple tests or processes need the same version. Binaries are stored in a user-specific cache directory and shared across test runs.

Cache Location

The cache directory is resolved by resolve_cache_dir in the following order:

1. PG_BINARY_CACHE_DIR environment variable if set
2. $XDG_CACHE_HOME/pg-embedded/binaries if XDG_CACHE_HOME is set
3. ~/.cache/pg-embedded/binaries if the home directory is available
4. /tmp/pg-embedded/binaries as last resort when none of the above are available

Cross-Process Coordination

The cache uses file-based locking to coordinate downloads across parallel test runners. Locks are per-version, allowing different versions to be downloaded concurrently.

Structs

BinaryCacheConfig

Configuration for the shared binary cache.

CacheLock

Guard that holds a file lock until dropped.

Enums

CacheLookupResult

Result of a cache lookup operation.

Functions

check_cache

Checks if the cache contains valid binaries for the given version.

copy_from_cache

Copies cached binaries to the target installation directory.

find_matching_cached_version

Finds a cached version that satisfies the given version requirement.

populate_cache

Populates the cache with binaries from the given source directory.

resolve_cache_dir

Resolves the binary cache directory from environment and XDG conventions.

try_populate_cache

Attempts to populate the cache after a download, logging warnings on failure.

try_use_cache

Attempts to use the cache, falling back gracefully on errors.