eckit::FileSpaceStrategies class
#include <eckit/filesystem/FileSpaceStrategies.h>

Strategies for selecting a filesystem from a set of candidates.

All strategies filter out filesystems that are unavailable or exceed candidateFileSystemMaxUsedPercent (default 99%). When no candidate survives filtering, strategies fall back to leastUsed().

Public static functions

static auto selectFileSystem(const std::vector<PathName>& fileSystems, const std::string& strategy) -> const PathName&: Dispatch to the named strategy.
static auto leastUsed(const std::vector<PathName>& fileSystems) -> const PathName&: Pick the filesystem with the most absolute free space.
static auto leastUsedPercent(const std::vector<PathName>& fileSystems) -> const PathName&: Pick the filesystem with the highest percentage of free space.
static auto roundRobin(const std::vector<PathName>& fileSystems) -> const PathName&: Cycle through candidates in order, seeded by PID.
static auto pureRandom(const std::vector<PathName>& fileSystems) -> const PathName&: Pick uniformly at random among candidates.
static auto weightedRandom(const std::vector<PathName>& fileSystems) -> const PathName&: Pick randomly, weighted by absolute available space.
static auto weightedRandomPercent(const std::vector<PathName>& fileSystems) -> const PathName&: Pick randomly, weighted by percentage of available space.
static auto binnedLeastUsed(const std::vector<PathName>& fileSystems) -> const PathName&: Pick randomly among candidates in the top availability bin.

Constructors, destructors, conversion operators

FileSpaceStrategies() deleted

Function documentation

static const PathName& eckit::FileSpaceStrategies::selectFileSystem(const std::vector<PathName>& fileSystems, const std::string& strategy)

Dispatch to the named strategy.

Parameters
fileSystems	candidate filesystem paths
strategy	strategy name — one of "roundRobin", "weightedRandom", "pureRandom", "weightedRandomPercent", "leastUsedPercent", "binnedLeastUsed"; any other value selects "leastUsed"
Returns	selected path

static const PathName& eckit::FileSpaceStrategies::leastUsed(const std::vector<PathName>& fileSystems)

Pick the filesystem with the most absolute free space.

Parameters
fileSystems	candidate filesystem paths
Returns	selected path

static const PathName& eckit::FileSpaceStrategies::leastUsedPercent(const std::vector<PathName>& fileSystems)

Pick the filesystem with the highest percentage of free space.

Parameters
fileSystems	candidate filesystem paths
Returns	selected path

static const PathName& eckit::FileSpaceStrategies::roundRobin(const std::vector<PathName>& fileSystems)

Cycle through candidates in order, seeded by PID.

Parameters
fileSystems	candidate filesystem paths
Returns	selected path

static const PathName& eckit::FileSpaceStrategies::pureRandom(const std::vector<PathName>& fileSystems)

Pick uniformly at random among candidates.

Parameters
fileSystems	candidate filesystem paths
Returns	selected path

static const PathName& eckit::FileSpaceStrategies::weightedRandom(const std::vector<PathName>& fileSystems)

Pick randomly, weighted by absolute available space.

Parameters
fileSystems	candidate filesystem paths
Returns	selected path

static const PathName& eckit::FileSpaceStrategies::weightedRandomPercent(const std::vector<PathName>& fileSystems)

Pick randomly, weighted by percentage of available space.

Parameters
fileSystems	candidate filesystem paths
Returns	selected path

static const PathName& eckit::FileSpaceStrategies::binnedLeastUsed(const std::vector<PathName>& fileSystems)

Pick randomly among candidates in the top availability bin.

Parameters
fileSystems	candidate filesystem paths
Returns	selected path

Divides the available-space range into eckit config value binnedLeastUsedNumBins bins (default 20). Only candidates in the topmost bin are eligible; one is chosen uniformly at random.