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-rw-r--r--lib/spack/llnl/util/lock.py136
-rw-r--r--lib/spack/spack/database.py130
2 files changed, 184 insertions, 82 deletions
diff --git a/lib/spack/llnl/util/lock.py b/lib/spack/llnl/util/lock.py
new file mode 100644
index 0000000000..05641475ed
--- /dev/null
+++ b/lib/spack/llnl/util/lock.py
@@ -0,0 +1,136 @@
+##############################################################################
+# Copyright (c) 2013, Lawrence Livermore National Security, LLC.
+# Produced at the Lawrence Livermore National Laboratory.
+#
+# This file is part of Spack.
+# Written by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://scalability-llnl.github.io/spack
+# Please also see the LICENSE file for our notice and the LGPL.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License (as published by
+# the Free Software Foundation) version 2.1 dated February 1999.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
+# conditions of the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
+import os
+import fcntl
+import errno
+import time
+import socket
+
+
+class Read_Lock_Instance(object):
+ """
+ A context manager for getting shared access to the object lock
+ Arguments are lock and timeout (default 5 minutes)
+ """
+ def __init__(self,lock,timeout = 300):
+ self._lock = lock
+ self._timeout = timeout
+ def __enter__(self):
+ self._lock.acquire_read(self._timeout)
+ def __exit__(self,type,value,traceback):
+ self._lock.release_read()
+
+
+class Write_Lock_Instance(object):
+ """
+ A context manager for getting exclusive access to the object lock
+ Arguments are lock and timeout (default 5 minutes)
+ """
+ def __init__(self,lock,timeout = 300):
+ self._lock = lock
+ self._timeout = timeout
+ def __enter__(self):
+ self._lock.acquire_write(self._timeout)
+ def __exit__(self,type,value,traceback):
+ self._lock.release_write()
+
+
+class Lock(object):
+ def __init__(self,file_path):
+ self._file_path = file_path
+ self._fd = os.open(file_path,os.O_RDWR)
+ self._reads = 0
+ self._writes = 0
+
+
+ def acquire_read(self,timeout):
+ """
+ Implements recursive lock. If held in both read and write mode,
+ the write lock will be maintained until all locks are released
+ """
+ if self._reads == 0 and self._writes == 0:
+ self._lock(fcntl.LOCK_SH,timeout)
+ self._reads += 1
+
+
+ def acquire_write(self,timeout):
+ """
+ Implements recursive lock
+ """
+ if self._writes == 0:
+ self._lock(fcntl.LOCK_EX,timeout)
+ self._writes += 1
+
+
+ def _lock(self,op,timeout):
+ """
+ The timeout is implemented using nonblocking flock()
+ to avoid using signals for timing
+ Write locks store pid and host information to the lock file
+ Read locks do not store data
+ """
+ total_time = 0
+ while total_time < timeout:
+ try:
+ fcntl.flock(self._fd, op | fcntl.LOCK_NB)
+ if op == fcntl.LOCK_EX:
+ with open(self._file_path,'w') as f:
+ f.write("pid = "+str(os.getpid())+", host = "+socket.getfqdn())
+ return
+ except IOError as error:
+ if error.errno == errno.EAGAIN or error.errno == EACCES:
+ pass
+ else:
+ raise
+ time.sleep(0.1)
+ total_time += 0.1
+
+
+ def release_read(self):
+ """
+ Assert there is a lock of the right type to release, recursive lock
+ """
+ assert self._reads > 0
+ if self._reads == 1 and self._writes == 0:
+ self._unlock()
+ self._reads -= 1
+
+
+ def release_write(self):
+ """
+ Assert there is a lock of the right type to release, recursive lock
+ """
+ assert self._writes > 0
+ if self._writes == 1 and self._reads == 0:
+ self._unlock()
+ self._writes -= 1
+
+
+ def _unlock(self):
+ """
+ Releases the lock regardless of mode. Note that read locks may be
+ masquerading as write locks at times, but this removes either.
+ """
+ fcntl.flock(self._fd,fcntl.LOCK_UN)
diff --git a/lib/spack/spack/database.py b/lib/spack/spack/database.py
index 5e8bb172b8..6a429b68a9 100644
--- a/lib/spack/spack/database.py
+++ b/lib/spack/spack/database.py
@@ -38,6 +38,7 @@ from external.yaml.error import MarkedYAMLError
import llnl.util.tty as tty
from llnl.util.filesystem import join_path
from llnl.util.lang import *
+from llnl.util.lock import *
import spack.error
import spack.spec
@@ -58,7 +59,7 @@ def _autospec(function):
class Database(object):
- def __init__(self,root,file_name="specDB.yaml"):
+ def __init__(self,root,file_name="_index.yaml"):
"""
Create an empty Database
Location defaults to root/specDB.yaml
@@ -67,28 +68,31 @@ class Database(object):
path: the path to the install of that package
dep_hash: a hash of the dependence DAG for that package
"""
- self.root = root
- self.file_name = file_name
- self.file_path = join_path(self.root,self.file_name)
+ self._root = root
+ self._file_name = file_name
+ self._file_path = join_path(self._root,self._file_name)
- self.lock_name = "db_lock"
- self.lock_path = join_path(self.root,self.lock_name)
+ self._lock_name = "_db_lock"
+ self._lock_path = join_path(self._root,self._lock_name)
+ if not os.path.exists(self._lock_path):
+ open(self._lock_path,'w').close()
+ self.lock = Lock(self._lock_path)
- self.data = []
- self.last_write_time = 0
+ self._data = []
+ self._last_write_time = 0
- def from_yaml(self,stream):
+ def _read_from_yaml(self,stream):
"""
Fill database from YAML, do not maintain old data
- Translate the spec portions from node-dict form to spec from
+ Translate the spec portions from node-dict form to spec form
"""
try:
file = yaml.load(stream)
except MarkedYAMLError, e:
raise SpackYAMLError("error parsing YAML database:", str(e))
- if file==None:
+ if file is None:
return
data = {}
@@ -104,51 +108,34 @@ class Database(object):
for idx in sph['deps']:
sph['spec'].dependencies[data[idx]['spec'].name] = data[idx]['spec']
- self.data = data.values()
+ self._data = data.values()
def read_database(self):
"""
Re-read Database from the data in the set location
If the cache is fresh, return immediately.
- Implemented with mkdir locking for the database file.
"""
if not self.is_dirty():
return
- lock=0
- while lock==0:
- try:
- os.mkdir(self.lock_path)
- lock=1
- except OSError as err:
- pass
-
- #The try statement ensures that a failure won't leave the
- #database locked to other processes.
- try:
- if os.path.isfile(self.file_path):
- with open(self.file_path,'r') as f:
- self.from_yaml(f)
- else:
+ if os.path.isfile(self._file_path):
+ with open(self._file_path,'r') as f:
+ self._read_from_yaml(f)
+ else:
#The file doesn't exist, construct empty data.
- self.data = []
- except:
- os.rmdir(self.lock_path)
- raise
-
- os.rmdir(self.lock_path)
+ self._data = []
- def write_database_to_yaml(self,stream):
+ def _write_database_to_yaml(self,stream):
"""
Replace each spec with its dict-node form
Then stream all data to YAML
"""
node_list = []
- spec_list = [sph['spec'] for sph in self.data]
+ spec_list = [sph['spec'] for sph in self._data]
- for sph in self.data:
+ for sph in self._data:
node = {}
deps = []
for name,spec in sph['spec'].dependencies.items():
@@ -167,46 +154,23 @@ class Database(object):
def write(self):
"""
Write the database to the standard location
- Implements mkdir locking for the database file
+ Everywhere that the database is written it is read
+ within the same lock, so there is no need to refresh
+ the database within write()
"""
- lock=0
- while lock==0:
- try:
- os.mkdir(self.lock_path)
- lock=1
- except OSError as err:
- pass
-
- #The try statement ensures that a failure won't leave the
- #database locked to other processes.
- try:
- with open(self.file_path,'w') as f:
- self.last_write_time = int(time.time())
- self.write_database_to_yaml(f)
- except:
- os.rmdir(self.lock_path)
- raise
-
- os.rmdir(self.lock_path)
-
-
- def get_index_of(self, spec):
- """
- Returns the index of a spec in the database
- If unable to find the spec it returns -1
- """
- for index, sph in enumerate(self.data):
- if sph['spec'] == spec:
- return index
- return -1
-
+ temp_name = os.getpid() + socket.getfqdn() + ".temp"
+ temp_file = path.join(self._root,temp_name)
+ with open(self.temp_path,'w') as f:
+ self._last_write_time = int(time.time())
+ self._write_database_to_yaml(f)
+ os.rename(temp_name,self._file_path)
def is_dirty(self):
"""
Returns true iff the database file exists
and was most recently written to by another spack instance.
"""
- return (os.path.isfile(self.file_path) and (os.path.getmtime(self.file_path) > self.last_write_time))
+ return (os.path.isfile(self._file_path) and (os.path.getmtime(self._file_path) > self._last_write_time))
# @_autospec
@@ -215,16 +179,15 @@ class Database(object):
Add the specified entry as a dict
Write the database back to memory
"""
- self.read_database()
-
sph = {}
sph['spec']=spec
sph['path']=path
sph['hash']=spec.dag_hash()
- self.data.append(sph)
-
- self.write()
+ with Write_Lock_Instance(self.lock,60):
+ self.read_database()
+ self._data.append(sph)
+ self.write()
@_autospec
@@ -234,13 +197,15 @@ class Database(object):
Searches for and removes the specified spec
Writes the database back to memory
"""
- self.read_database()
+ with Write_Lock_Instance(self.lock,60):
+ self.read_database()
- for sp in self.data:
- if sp['hash'] == spec.dag_hash() and sp['spec'] == spec:
- self.data.remove(sp)
+ for sp in self._data:
+ #Not sure the hash comparison is necessary
+ if sp['hash'] == spec.dag_hash() and sp['spec'] == spec:
+ self._data.remove(sp)
- self.write()
+ self.write()
@_autospec
@@ -272,10 +237,11 @@ class Database(object):
Read installed package names from the database
and return their specs
"""
- self.read_database()
+ with Read_Lock_Instance(self.lock,60):
+ self.read_database()
installed = []
- for sph in self.data:
+ for sph in self._data:
installed.append(sph['spec'])
return installed