diff options
| -rw-r--r-- | includes/FileLock.h | 12 | ||||
| -rw-r--r-- | rts/Hash.c | 9 | ||||
| -rw-r--r-- | rts/Hash.h | 7 | ||||
| -rw-r--r-- | rts/Linker.c | 2 | ||||
| -rw-r--r-- | rts/RtsStartup.c | 11 | ||||
| -rw-r--r-- | rts/posix/FileLock.c | 121 |
6 files changed, 156 insertions, 6 deletions
diff --git a/includes/FileLock.h b/includes/FileLock.h new file mode 100644 index 0000000000..3fc1a81aec --- /dev/null +++ b/includes/FileLock.h @@ -0,0 +1,12 @@ +/* ----------------------------------------------------------------------------- + * + * (c) The GHC Team, 2007 + * + * File locking support as required by Haskell 98 + * + * ---------------------------------------------------------------------------*/ + +void initFileLocking(void); +void freeFileLocking(void); +int lockFile(int fd, dev_t dev, ino_t ino, int for_writing); +int unlockFile(int fd); diff --git a/rts/Hash.c b/rts/Hash.c index 1d80640c4a..033ccb3e73 100644 --- a/rts/Hash.c +++ b/rts/Hash.c @@ -35,9 +35,6 @@ struct hashlist { typedef struct hashlist HashList; -typedef int HashFunction(HashTable *table, StgWord key); -typedef int CompareFunction(StgWord key1, StgWord key2); - struct hashtable { int split; /* Next bucket to split when expanding */ int max; /* Max bucket of smaller table */ @@ -55,7 +52,7 @@ struct hashtable { * next bucket to be split, re-hash using the larger table. * -------------------------------------------------------------------------- */ -static int +int hashWord(HashTable *table, StgWord key) { int bucket; @@ -73,7 +70,7 @@ hashWord(HashTable *table, StgWord key) return bucket; } -static int +int hashStr(HashTable *table, char *key) { int h, bucket; @@ -347,7 +344,7 @@ freeHashTable(HashTable *table, void (*freeDataFun)(void *) ) * initializing all of the first segment's hash buckets to NULL. * -------------------------------------------------------------------------- */ -static HashTable * +HashTable * allocHashTable_(HashFunction *hash, CompareFunction *compare) { HashTable *table; diff --git a/rts/Hash.h b/rts/Hash.h index fb83fdfa9e..d16f9ae9c1 100644 --- a/rts/Hash.h +++ b/rts/Hash.h @@ -32,6 +32,13 @@ HashTable * allocStrHashTable ( void ); #define removeStrHashTable(table, key, data) \ (removeHashTable(table, (StgWord)key, data)) +/* Hash tables for arbitrary keys */ +typedef int HashFunction(HashTable *table, StgWord key); +typedef int CompareFunction(StgWord key1, StgWord key2); +HashTable * allocHashTable_(HashFunction *hash, CompareFunction *compare); +int hashWord(HashTable *table, StgWord key); +int hashStr(HashTable *table, char *key); + /* Freeing hash tables */ void freeHashTable ( HashTable *table, void (*freeDataFun)(void *) ); diff --git a/rts/Linker.c b/rts/Linker.c index 81709f7819..7793801325 100644 --- a/rts/Linker.c +++ b/rts/Linker.c @@ -174,6 +174,8 @@ typedef struct _RtsSymbolVal { #if !defined (mingw32_HOST_OS) #define RTS_POSIX_ONLY_SYMBOLS \ + Sym(lockFile) \ + Sym(unlockFile) \ SymX(signal_handlers) \ SymX(stg_sig_install) \ Sym(nocldstop) diff --git a/rts/RtsStartup.c b/rts/RtsStartup.c index cdb45c60f2..4f84468b0a 100644 --- a/rts/RtsStartup.c +++ b/rts/RtsStartup.c @@ -33,6 +33,7 @@ #include "RtsTypeable.h" #include "Stable.h" #include "Hpc.h" +#include "FileLock.h" #if defined(RTS_GTK_FRONTPANEL) #include "FrontPanel.h" @@ -238,6 +239,11 @@ hs_init(int *argc, char **argv[]) /* initialise the shared Typeable store */ initTypeableStore(); + /* initialise file locking, if necessary */ +#if !defined(mingw32_HOST_OS) + initFileLocking(); +#endif + #if defined(DEBUG) /* initialise thread label table (tso->char*) */ initThreadLabelTable(); @@ -462,6 +468,11 @@ hs_exit_(rtsBool wait_foreign) /* free shared Typeable store */ exitTypeableStore(); + /* free file locking tables, if necessary */ +#if !defined(mingw32_HOST_OS) + freeFileLocking(); +#endif + /* free the stable pointer table */ exitStablePtrTable(); diff --git a/rts/posix/FileLock.c b/rts/posix/FileLock.c new file mode 100644 index 0000000000..436d8c9da5 --- /dev/null +++ b/rts/posix/FileLock.c @@ -0,0 +1,121 @@ +/* ----------------------------------------------------------------------------- + * + * (c) The GHC Team, 2007 + * + * File locking support as required by Haskell 98 + * + * ---------------------------------------------------------------------------*/ + +#include "Rts.h" +#include "Hash.h" +#include "FileLock.h" +#include "RtsUtils.h" + +#include <unistd.h> +#include <sys/stat.h> +#include <errno.h> + +typedef struct { + dev_t device; + ino_t inode; + int readers; // >0 : readers, <0 : writers +} Lock; + +// Two hash tables. The first maps objects (device/inode pairs) to +// Lock objects containing the number of active readers or writers. The +// second maps file descriptors to lock objects, so that we can unlock +// by FD without needing to fstat() again. +static HashTable *obj_hash; +static HashTable *fd_hash; + +static int cmpLocks(StgWord w1, StgWord w2) +{ + Lock *l1 = (Lock *)w1; + Lock *l2 = (Lock *)w2; + return (l1->device == l2->device && l1->inode == l2->inode); +} + +static int hashLock(HashTable *table, StgWord w) +{ + Lock *l = (Lock *)w; + // Just xor the dev_t with the ino_t, hope this is good enough. + return hashWord(table, (StgWord)l->inode ^ (StgWord)l->device); +} + +void +initFileLocking(void) +{ + obj_hash = allocHashTable_(hashLock, cmpLocks); + fd_hash = allocHashTable(); /* ordinary word-based table */ +} + +static void +freeLock(void *lock) +{ + stgFree(lock); +} + +void +freeFileLocking(void) +{ + freeHashTable(obj_hash, freeLock); + freeHashTable(fd_hash, NULL); +} + +int +lockFile(int fd, dev_t dev, ino_t ino, int for_writing) +{ + Lock key, *lock; + + key.device = dev; + key.inode = ino; + + lock = lookupHashTable(obj_hash, (StgWord)&key); + + if (lock == NULL) + { + lock = stgMallocBytes(sizeof(Lock), "lockFile"); + lock->device = dev; + lock->inode = ino; + lock->readers = for_writing ? -1 : 1; + insertHashTable(obj_hash, (StgWord)lock, (void *)lock); + insertHashTable(fd_hash, fd, lock); + return 0; + } + else + { + // single-writer/multi-reader locking: + if (for_writing || lock->readers < 0) { + return -1; + } + lock->readers++; + return 0; + } +} + +int +unlockFile(int fd) +{ + Lock *lock; + + lock = lookupHashTable(fd_hash, fd); + if (lock == NULL) { + // errorBelch("unlockFile: fd %d not found", fd); + // This is normal: we didn't know when calling unlockFile + // whether this FD referred to a locked file or not. + return 1; + } + + if (lock->readers < 0) { + lock->readers++; + } else { + lock->readers--; + } + + if (lock->readers == 0) { + removeHashTable(obj_hash, (StgWord)lock, NULL); + stgFree(lock); + } + removeHashTable(fd_hash, fd, NULL); + return 0; +} |