Documentation
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Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func NewLazyDirectory ¶
func NewLazyDirectory(directoryOpener DirectoryOpener) filesystem.Directory
NewLazyDirectory creates a directory handle that forwards all calls to a directory that is created on demand. The primary use case for this adapter is for the FUSE-based runner.
A runner process may get started before the worker is able to create its FUSE mount point. This would cause the runner to obtain a handle to the build directory underneath the FUSE mount, causing builds to fail due to missing input files.
Relatedly, if the worker would start before the runner, but end up crashing/restarting, the runner would still have a directory handle pointing to a stale FUSE mount.
This wrapper prevents these problems by ensuring that we never hold on to a file descriptor to the build directory.
Types ¶
type DirectoryOpener ¶
type DirectoryOpener func() (filesystem.DirectoryCloser, error)
DirectoryOpener is a callback that is used by LazyDirectory to open the underlying directory on demand.
type SectorAllocator ¶
type SectorAllocator interface {
// Allocate a contiguous range of sectors.
//
// Under high utilization, it may not be possible to allocate
// all space contiguously. In that case, this function returns
// fewer sectors than requested. Repeated calls to this function
// are necessary to request the desired amount of space, albeit
// fragmented.
//
// Sector numbers handed out by this function start at one.
// Zero can be used by the user of this interface for special
// purposes (e.g., sparse files).
AllocateContiguous(maximum int) (uint32, int, error)
// Free a contiguous range of sectors. It is invalid to call
// this function with the first sector number being zero.
FreeContiguous(first uint32, count int)
// Free a potentially fragmented list of sectors. Elements with
// value zero are ignored.
FreeList(sectors []uint32)
}
SectorAllocator is used by BlockDeviceBackedFilePool to allocate space on the block device that is needed to store files.
func NewBitmapSectorAllocator ¶
func NewBitmapSectorAllocator(sectorCount uint32) SectorAllocator
NewBitmapSectorAllocator creates a SectorAllocator that stores information on which sectors are allocated in a bitmap. Sectors are allocated by sequentially scanning the bitmap, continuing where previous calls left off.
Due to its simplicity, this allocator would be prone to heavy fragmentation if used for general purpose file systems. For FilePool this is not a problem, because files have short lifetimes. Fragmentation disappears entirely when a worker goes idle, causing the FilePool to go empty.
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