/// <summary>
/// Computes the existence of a path when not cached. For graph file systems the existence state of all paths
/// is statically known, so non-existent is returned here as not finding a cached path means it does not appear
/// in graph file system.
/// </summary>
private Possible <PathExistence> ComputeAndAddCacheRealFileSystemExistence(AbsolutePath path, FileSystemViewMode mode, bool?isReadOnly = default)
{
Contract.Requires(mode == FileSystemViewMode.Real);
// Optimization. Check if the path can be determined to not exist based on a parent path without
// checking file system
if (m_inferNonExistenceBasedOnParentPathInRealFileSystem &&
TryInferNonExistenceBasedOnParentPathInRealFileSystem(path, out var trackedParentPath, out var intermediateParentPath) &&
TrackRealFileSystemAbsentChildPath(trackedParentPath, descendantPath: path))
{
return(PathExistence.Nonexistent);
}
// TODO: Some kind of strategy to trigger enumerating directories with commonly probed members
// TODO: Perhaps probabilistically enumerate based on hash of path and some counter
var possibleExistence = LocalDiskFileSystem.TryProbeAndTrackPathForExistence(path.Expand(PathTable), isReadOnly);
Counters.IncrementCounter(FileSystemViewCounters.RealFileSystemDiskProbes);
if (possibleExistence.Succeeded)
{
GetOrAddExistence(path, mode, possibleExistence.Result);
}
return(possibleExistence);
}
private bool TrackRealFileSystemAbsentChildPath(AbsolutePath trackedParentPath, AbsolutePath descendantPath)
{
var path = descendantPath;
while (path.IsValid && path != trackedParentPath)
{
GetOrAddExistence(path, FileSystemViewMode.Real, PathExistence.Nonexistent);
path = path.GetParent(PathTable);
}
return(LocalDiskFileSystem.TrackAbsentPath(trackedParentPath, descendantPath));
}
/// <summary>
/// Queries the existence and members of a directory in the specified file system mode
/// </summary>
public Possible <PathExistence> TryEnumerateDirectory(AbsolutePath path, FileSystemViewMode mode, Action <string, AbsolutePath, PathExistence> handleEntry, bool cachePathExistence = true)
{
FileSystemEntry entry;
PathExistence existence;
if (PathExistenceCache.TryGetValue(path, out entry) && entry.TryGetExistence(mode, out existence))
{
if (existence == PathExistence.Nonexistent)
{
return(existence);
}
if (existence == PathExistence.ExistsAsFile)
{
bool isDirectorySymlinkOrJunction = false;
if (entry.HasFlag(FileSystemEntryFlags.CheckedIsDirectorySymlink))
{
isDirectorySymlinkOrJunction = entry.HasFlag(FileSystemEntryFlags.IsDirectorySymlink);
}
else
{
isDirectorySymlinkOrJunction = FileUtilities.IsDirectorySymlinkOrJunction(path.ToString(PathTable));
PathExistenceCache.AddOrUpdate(path, false,
(key, data) => { throw Contract.AssertFailure("Entry should already be added for path"); },
(key, data, oldValue) => oldValue.SetFlag(
FileSystemEntryFlags.CheckedIsDirectorySymlink
| (isDirectorySymlinkOrJunction ? FileSystemEntryFlags.IsDirectorySymlink : FileSystemEntryFlags.None)));
}
if (!isDirectorySymlinkOrJunction)
{
return(existence);
}
}
// For graph file systems, directory members can be determined by overlaying path table with existence state in-memory
// For real file system, this same is true if the directory has already been enumerated
if (mode != FileSystemViewMode.Real || ((entry.Flags & FileSystemEntryFlags.IsRealFileSystemEnumerated) != 0))
{
foreach (var childPathValue in PathTable.EnumerateImmediateChildren(path.Value))
{
var childPath = new AbsolutePath(childPathValue);
PathExistence childExistence;
if (TryGetKnownPathExistence(childPath, mode, out childExistence) && childExistence != PathExistence.Nonexistent)
{
var entryName = childPath.GetName(PathTable).ToString(PathTable.StringTable);
handleEntry(entryName, childPath, childExistence);
}
}
return(existence);
}
}
if (mode == FileSystemViewMode.Real)
{
var handleDirectoryEntry = new Action <string, FileAttributes>((entryName, entryAttributes) =>
{
// Reparse points are always treated as files. Otherwise, honor the directory attribute to determine
// existence
var childExistence = (entryAttributes & FileAttributes.ReparsePoint) != 0 ?
PathExistence.ExistsAsFile :
(entryAttributes & FileAttributes.Directory) != 0 ?
PathExistence.ExistsAsDirectory :
PathExistence.ExistsAsFile;
var childPath = path.Combine(PathTable, entryName);
childExistence = GetOrAddExistence(childPath, mode, childExistence, updateParents: false);
// NOTE: Because we are caching file system state in memory, it is possible that the existence state of
// files does not match the state from the file system.
if (childExistence != PathExistence.Nonexistent)
{
handleEntry(entryName, childPath, childExistence);
}
});
Counters.IncrementCounter(FileSystemViewCounters.RealFileSystemEnumerations);
if (cachePathExistence)
{
Possible <PathExistence> possibleExistence;
using (Counters.StartStopwatch(FileSystemViewCounters.RealFileSystemEnumerationsDuration))
{
possibleExistence = LocalDiskFileSystem.TryEnumerateDirectoryAndTrackMembership(
path,
handleDirectoryEntry,
// This method is called during observed input processing. Currently, we simply include all entries.
// TODO: In the future, we may want to restrict it based on pip's untracked scopes/paths.
shouldIncludeEntry: null /* include all entries */);
}
if (possibleExistence.Succeeded)
{
existence = GetOrAddExistence(path, mode, possibleExistence.Result);
PathExistenceCache.AddOrUpdate(path, false,
(key, data) => { throw Contract.AssertFailure("Entry should already be added for path"); },
(key, data, oldValue) => oldValue.SetFlag(FileSystemEntryFlags.IsRealFileSystemEnumerated));
return(existence);
}
return(possibleExistence);
}
using (Counters.StartStopwatch(FileSystemViewCounters.RealFileSystemEnumerationsDuration))
{
var possibleFingerprintResult = DirectoryMembershipTrackingFingerprinter.ComputeFingerprint(
path.Expand(PathTable).ExpandedPath,
handleEntry: handleDirectoryEntry);
return(possibleFingerprintResult.Succeeded
? new Possible <PathExistence>(possibleFingerprintResult.Result.PathExistence)
: new Possible <PathExistence>(possibleFingerprintResult.Failure));
}
}
else if (ExistsInGraphFileSystem(PipGraph.TryGetLatestFileArtifactForPath(path), mode))
{
return(PathExistence.ExistsAsFile);
}
return(PathExistence.Nonexistent);
}
/// <summary>
/// Queries the existence and members of a directory in the specified file system mode
/// </summary>
public Possible <PathExistence> TryEnumerateDirectory(AbsolutePath path, FileSystemViewMode mode, Action <string, AbsolutePath, PathExistence> handleEntry, bool cachePathExistence = true)
{
FileSystemEntry entry;
PathExistence existence;
if (PathExistenceCache.TryGetValue(path, out entry) && entry.TryGetExistence(mode, out existence))
{
if (existence != PathExistence.ExistsAsDirectory)
{
return(existence);
}
// For graph file systems, directory members can be determined by overlaying path table with existence state in-memory
// For real file system, this same is true if the directory has already been enumerated
if (mode != FileSystemViewMode.Real || ((entry.Flags & FileSystemEntryFlags.IsRealFileSystemEnumerated) != 0))
{
foreach (var childPathValue in PathTable.EnumerateImmediateChildren(path.Value))
{
var childPath = new AbsolutePath(childPathValue);
PathExistence childExistence;
if (TryGetKnownPathExistence(childPath, mode, out childExistence) && childExistence != PathExistence.Nonexistent)
{
var entryName = childPath.GetName(PathTable).ToString(PathTable.StringTable);
handleEntry(entryName, childPath, childExistence);
}
}
return(existence);
}
}
if (mode == FileSystemViewMode.Real)
{
var handleDirectoryEntry = new Action <string, FileAttributes>((entryName, entryAttributes) =>
{
var childExistence = (entryAttributes & FileAttributes.Directory) != 0 ? PathExistence.ExistsAsDirectory : PathExistence.ExistsAsFile;
var childPath = path.Combine(PathTable, entryName);
childExistence = GetOrAddExistence(childPath, mode, childExistence, updateParents: false);
// NOTE: Because we are caching file system state in memory, it is possible that the existence state of
// files does not match the state from the file system.
if (childExistence != PathExistence.Nonexistent)
{
handleEntry(entryName, childPath, childExistence);
}
});
Counters.IncrementCounter(FileSystemViewCounters.RealFileSystemEnumerations);
if (cachePathExistence)
{
Possible <PathExistence> possibleExistence;
using (Counters.StartStopwatch(FileSystemViewCounters.RealFileSystemEnumerationsDuration))
{
possibleExistence = LocalDiskFileSystem.TryEnumerateDirectoryAndTrackMembership(path, handleDirectoryEntry);
}
if (possibleExistence.Succeeded)
{
existence = GetOrAddExistence(path, mode, possibleExistence.Result);
PathExistenceCache.AddOrUpdate(path, false,
(key, data) => { throw Contract.AssertFailure("Entry should already be added for path"); },
(key, data, oldValue) => oldValue.SetFlag(FileSystemEntryFlags.IsRealFileSystemEnumerated));
return(existence);
}
return(possibleExistence);
}
using (Counters.StartStopwatch(FileSystemViewCounters.RealFileSystemEnumerationsDuration))
{
var possibleFingerprintResult = DirectoryMembershipTrackingFingerprinter.ComputeFingerprint(
path.Expand(PathTable).ExpandedPath,
handleEntry: handleDirectoryEntry);
return(possibleFingerprintResult.Succeeded
? new Possible <PathExistence>(possibleFingerprintResult.Result.PathExistence)
: new Possible <PathExistence>(possibleFingerprintResult.Failure));
}
}
else if (ExistsInGraphFileSystem(PipGraph.TryGetLatestFileArtifactForPath(path), mode))
{
return(PathExistence.ExistsAsFile);
}
return(PathExistence.Nonexistent);
}
