diff options
Diffstat (limited to 'libpod/lock/shm/shm_lock.go')
| -rw-r--r-- | libpod/lock/shm/shm_lock.go | 216 |
1 files changed, 0 insertions, 216 deletions
diff --git a/libpod/lock/shm/shm_lock.go b/libpod/lock/shm/shm_lock.go deleted file mode 100644 index be5e5148f..000000000 --- a/libpod/lock/shm/shm_lock.go +++ /dev/null @@ -1,216 +0,0 @@ -package shm - -// #cgo LDFLAGS: -lrt -lpthread -// #include <stdlib.h> -// #include "shm_lock.h" -// const uint32_t bitmap_size_c = BITMAP_SIZE; -import "C" - -import ( - "runtime" - "syscall" - "unsafe" - - "github.com/pkg/errors" - "github.com/sirupsen/logrus" -) - -var ( - // BitmapSize is the size of the bitmap used when managing SHM locks. - // an SHM lock manager's max locks will be rounded up to a multiple of - // this number. - BitmapSize uint32 = uint32(C.bitmap_size_c) -) - -// SHMLocks is a struct enabling POSIX semaphore locking in a shared memory -// segment. -type SHMLocks struct { // nolint - lockStruct *C.shm_struct_t - maxLocks uint32 - valid bool -} - -// CreateSHMLock sets up a shared-memory segment holding a given number of POSIX -// semaphores, and returns a struct that can be used to operate on those locks. -// numLocks must not be 0, and may be rounded up to a multiple of the bitmap -// size used by the underlying implementation. -func CreateSHMLock(path string, numLocks uint32) (*SHMLocks, error) { - if numLocks == 0 { - return nil, errors.Wrapf(syscall.EINVAL, "number of locks must greater than 0 0") - } - - locks := new(SHMLocks) - - cPath := C.CString(path) - defer C.free(unsafe.Pointer(cPath)) - - var errCode C.int - lockStruct := C.setup_lock_shm(cPath, C.uint32_t(numLocks), &errCode) - if lockStruct == nil { - // We got a null pointer, so something errored - return nil, errors.Wrapf(syscall.Errno(-1*errCode), "failed to create %d locks in %s", numLocks, path) - } - - locks.lockStruct = lockStruct - locks.maxLocks = uint32(lockStruct.num_locks) - locks.valid = true - - logrus.Debugf("Initialized SHM lock manager at path %s", path) - - return locks, nil -} - -// OpenSHMLock opens an existing shared-memory segment holding a given number of -// POSIX semaphores. numLocks must match the number of locks the shared memory -// segment was created with. -func OpenSHMLock(path string, numLocks uint32) (*SHMLocks, error) { - if numLocks == 0 { - return nil, errors.Wrapf(syscall.EINVAL, "number of locks must greater than 0") - } - - locks := new(SHMLocks) - - cPath := C.CString(path) - defer C.free(unsafe.Pointer(cPath)) - - var errCode C.int - lockStruct := C.open_lock_shm(cPath, C.uint32_t(numLocks), &errCode) - if lockStruct == nil { - // We got a null pointer, so something errored - return nil, errors.Wrapf(syscall.Errno(-1*errCode), "failed to open %d locks in %s", numLocks, path) - } - - locks.lockStruct = lockStruct - locks.maxLocks = numLocks - locks.valid = true - - return locks, nil -} - -// GetMaxLocks returns the maximum number of locks in the SHM -func (locks *SHMLocks) GetMaxLocks() uint32 { - return locks.maxLocks -} - -// Close closes an existing shared-memory segment. -// The segment will be rendered unusable after closing. -// WARNING: If you Close() while there are still locks locked, these locks may -// fail to release, causing a program freeze. -// Close() is only intended to be used while testing the locks. -func (locks *SHMLocks) Close() error { - if !locks.valid { - return errors.Wrapf(syscall.EINVAL, "locks have already been closed") - } - - locks.valid = false - - retCode := C.close_lock_shm(locks.lockStruct) - if retCode < 0 { - // Negative errno returned - return syscall.Errno(-1 * retCode) - } - - return nil -} - -// AllocateSemaphore allocates a semaphore from a shared-memory segment for use -// by a container or pod. -// Returns the index of the semaphore that was allocated. -// Allocations past the maximum number of locks given when the SHM segment was -// created will result in an error, and no semaphore will be allocated. -func (locks *SHMLocks) AllocateSemaphore() (uint32, error) { - if !locks.valid { - return 0, errors.Wrapf(syscall.EINVAL, "locks have already been closed") - } - - // This returns a U64, so we have the full u32 range available for - // semaphore indexes, and can still return error codes. - retCode := C.allocate_semaphore(locks.lockStruct) - if retCode < 0 { - // Negative errno returned - return 0, syscall.Errno(-1 * retCode) - } - - return uint32(retCode), nil -} - -// DeallocateSemaphore frees a semaphore in a shared-memory segment so it can be -// reallocated to another container or pod. -// The given semaphore must be already allocated, or an error will be returned. -func (locks *SHMLocks) DeallocateSemaphore(sem uint32) error { - if !locks.valid { - return errors.Wrapf(syscall.EINVAL, "locks have already been closed") - } - - if sem > locks.maxLocks { - return errors.Wrapf(syscall.EINVAL, "given semaphore %d is higher than maximum locks count %d", sem, locks.maxLocks) - } - - retCode := C.deallocate_semaphore(locks.lockStruct, C.uint32_t(sem)) - if retCode < 0 { - // Negative errno returned - return syscall.Errno(-1 * retCode) - } - - return nil -} - -// LockSemaphore locks the given semaphore. -// If the semaphore is already locked, LockSemaphore will block until the lock -// can be acquired. -// There is no requirement that the given semaphore be allocated. -// This ensures that attempts to lock a container after it has been deleted, -// but before the caller has queried the database to determine this, will -// succeed. -func (locks *SHMLocks) LockSemaphore(sem uint32) error { - if !locks.valid { - return errors.Wrapf(syscall.EINVAL, "locks have already been closed") - } - - if sem > locks.maxLocks { - return errors.Wrapf(syscall.EINVAL, "given semaphore %d is higher than maximum locks count %d", sem, locks.maxLocks) - } - - // For pthread mutexes, we have to guarantee lock and unlock happen in - // the same thread. - runtime.LockOSThread() - - retCode := C.lock_semaphore(locks.lockStruct, C.uint32_t(sem)) - if retCode < 0 { - // Negative errno returned - return syscall.Errno(-1 * retCode) - } - - return nil -} - -// UnlockSemaphore unlocks the given semaphore. -// Unlocking a semaphore that is already unlocked with return EBUSY. -// There is no requirement that the given semaphore be allocated. -// This ensures that attempts to lock a container after it has been deleted, -// but before the caller has queried the database to determine this, will -// succeed. -func (locks *SHMLocks) UnlockSemaphore(sem uint32) error { - if !locks.valid { - return errors.Wrapf(syscall.EINVAL, "locks have already been closed") - } - - if sem > locks.maxLocks { - return errors.Wrapf(syscall.EINVAL, "given semaphore %d is higher than maximum locks count %d", sem, locks.maxLocks) - } - - retCode := C.unlock_semaphore(locks.lockStruct, C.uint32_t(sem)) - if retCode < 0 { - // Negative errno returned - return syscall.Errno(-1 * retCode) - } - - // For pthread mutexes, we have to guarantee lock and unlock happen in - // the same thread. - // OK if we take multiple locks - UnlockOSThread() won't actually unlock - // until the number of calls equals the number of calls to - // LockOSThread() - runtime.UnlockOSThread() - - return nil -} |