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Commit deddffab authored by Jeremy Hylton's avatar Jeremy Hylton
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Let emacs reformat the long comment lbock. 

(Thanks for the comments, Toby!)
parent a0a80adf
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src/Persistence/cPickleCache.c
View file @ deddffab
...@@ -21,58 +21,57 @@ Regime 1: Persistent Classes ...@@ -21,58 +21,57 @@ Regime 1: Persistent Classes
Persistent Classes are part of ZClasses. They are stored in the Persistent Classes are part of ZClasses. They are stored in the
self->data dictionary, and are never garbage collected. self->data dictionary, and are never garbage collected.
The klass_items() method returns a sequence of (oid,object) tuples The klass_items() method returns a sequence of (oid,object) tuples for
for every Persistent Class, which should make it possible to every Persistent Class, which should make it possible to implement
implement garbage collection in Python if necessary. garbage collection in Python if necessary.
Regime 2: Ghost Objects Regime 2: Ghost Objects
There is no benefit to keeping a ghost object which has no There is no benefit to keeping a ghost object which has no external
external references, therefore a weak reference scheme is references, therefore a weak reference scheme is used to ensure that
used to ensure that ghost objects are removed from memory ghost objects are removed from memory as soon as possible, when the
as soon as possible, when the last external reference is lost. last external reference is lost.
Ghost objects are stored in the self->data dictionary. Normally Ghost objects are stored in the self->data dictionary. Normally a
a dictionary keeps a strong reference on its values, however dictionary keeps a strong reference on its values, however this
this reference count is 'stolen'. reference count is 'stolen'.
This weak reference scheme leaves a dangling reference, in the This weak reference scheme leaves a dangling reference, in the
dictionary, when the last external reference is lost. To clean up dictionary, when the last external reference is lost. To clean up this
this dangling reference the persistent object dealloc function dangling reference the persistent object dealloc function calls
calls self->cache->_oid_unreferenced(self->oid). The cache looks self->cache->_oid_unreferenced(self->oid). The cache looks up the oid
up the oid in the dictionary, ensures it points to an object whose in the dictionary, ensures it points to an object whose reference
reference count is zero, then removes it from the dictionary. Before count is zero, then removes it from the dictionary. Before removing
removing the object from the dictionary it must temporarily resurrect the object from the dictionary it must temporarily resurrect the
the object in much the same way that class instances are resurrected object in much the same way that class instances are resurrected
before their __del__ is called. before their __del__ is called.
Since ghost objects are stored under a different regime to Since ghost objects are stored under a different regime to non-ghost
non-ghost objects, an extra ghostify function in cPersistenceAPI objects, an extra ghostify function in cPersistenceAPI replaces
replaces self->state=GHOST_STATE assignments that were common in self->state=GHOST_STATE assignments that were common in other
other persistent classes (such as BTrees). persistent classes (such as BTrees).
Regime 3: Non-Ghost Objects Regime 3: Non-Ghost Objects
Non-ghost objects are stored in two data structures. Firstly, in Non-ghost objects are stored in two data structures. Firstly, in the
the dictionary along with everything else, with a *strong* reference. dictionary along with everything else, with a *strong* reference.
Secondly, they are stored in a doubly-linked-list which encodes Secondly, they are stored in a doubly-linked-list which encodes the
the order in which these objects have been most recently used. order in which these objects have been most recently used.
The doubly-link-list nodes contain next and previous pointers The doubly-link-list nodes contain next and previous pointers linking
linking together the cache and all non-ghost persistent objects. together the cache and all non-ghost persistent objects.
The node embedded in the cache is the home position. On every The node embedded in the cache is the home position. On every
attribute access a non-ghost object will relink itself just attribute access a non-ghost object will relink itself just behind the
behind the home position in the ring. Objects accessed least home position in the ring. Objects accessed least recently will
recently will eventually find themselves positioned after eventually find themselves positioned after the home position.
the home position.
Occasionally other nodes are temporarily inserted in the ring as
Occasionally other nodes are temporarily inserted in the ring position markers. The cache contains a ring_lock flag which must be
as position markers. The cache contains a ring_lock flag which set and unset before and after doing so. Only if the flag is unset can
must be set and unset before and after doing so. Only if the flag the cache assume that all nodes are either his own home node, or nodes
is unset can the cache assume that all nodes are either his own from persistent objects. This assumption is useful during the garbage
home node, or nodes from persistent objects. This assumption is collection process.
useful during the garbage collection process.
The number of non-ghost objects is counted in self->non_ghost_count. The number of non-ghost objects is counted in self->non_ghost_count.
The garbage collection process consists of traversing the ring, and The garbage collection process consists of traversing the ring, and
...@@ -80,17 +79,16 @@ deactivating (that is, turning into a ghost) every object until ...@@ -80,17 +79,16 @@ deactivating (that is, turning into a ghost) every object until
self->non_ghost_count is down to the target size, or until it self->non_ghost_count is down to the target size, or until it
reaches the home position again. reaches the home position again.
Note that objects in the sticky or changed states are still kept Note that objects in the sticky or changed states are still kept in
in the ring, however they can not be deactivated. The garbage the ring, however they can not be deactivated. The garbage collection
collection process must skip such objects, rather than deactivating process must skip such objects, rather than deactivating them.
them.
*/ */
static char cPickleCache_doc_string[] = static char cPickleCache_doc_string[] =
"Defines the PickleCache used by ZODB Connection objects.\n" "Defines the PickleCache used by ZODB Connection objects.\n"
"\n" "\n"
"$Id: cPickleCache.c,v 1.52 2002/04/03 17:20:33 htrd Exp $\n"; "$Id: cPickleCache.c,v 1.53 2002/04/03 17:53:27 jeremy Exp $\n";
#define ASSIGN(V,E) {PyObject *__e; __e=(E); Py_XDECREF(V); (V)=__e;} #define ASSIGN(V,E) {PyObject *__e; __e=(E); Py_XDECREF(V); (V)=__e;}
#define UNLESS(E) if(!(E)) #define UNLESS(E) if(!(E))
......
src/ZODB/cPickleCache.c
View file @ deddffab
...@@ -21,58 +21,57 @@ Regime 1: Persistent Classes ...@@ -21,58 +21,57 @@ Regime 1: Persistent Classes
Persistent Classes are part of ZClasses. They are stored in the Persistent Classes are part of ZClasses. They are stored in the
self->data dictionary, and are never garbage collected. self->data dictionary, and are never garbage collected.
The klass_items() method returns a sequence of (oid,object) tuples The klass_items() method returns a sequence of (oid,object) tuples for
for every Persistent Class, which should make it possible to every Persistent Class, which should make it possible to implement
implement garbage collection in Python if necessary. garbage collection in Python if necessary.
Regime 2: Ghost Objects Regime 2: Ghost Objects
There is no benefit to keeping a ghost object which has no There is no benefit to keeping a ghost object which has no external
external references, therefore a weak reference scheme is references, therefore a weak reference scheme is used to ensure that
used to ensure that ghost objects are removed from memory ghost objects are removed from memory as soon as possible, when the
as soon as possible, when the last external reference is lost. last external reference is lost.
Ghost objects are stored in the self->data dictionary. Normally Ghost objects are stored in the self->data dictionary. Normally a
a dictionary keeps a strong reference on its values, however dictionary keeps a strong reference on its values, however this
this reference count is 'stolen'. reference count is 'stolen'.
This weak reference scheme leaves a dangling reference, in the This weak reference scheme leaves a dangling reference, in the
dictionary, when the last external reference is lost. To clean up dictionary, when the last external reference is lost. To clean up this
this dangling reference the persistent object dealloc function dangling reference the persistent object dealloc function calls
calls self->cache->_oid_unreferenced(self->oid). The cache looks self->cache->_oid_unreferenced(self->oid). The cache looks up the oid
up the oid in the dictionary, ensures it points to an object whose in the dictionary, ensures it points to an object whose reference
reference count is zero, then removes it from the dictionary. Before count is zero, then removes it from the dictionary. Before removing
removing the object from the dictionary it must temporarily resurrect the object from the dictionary it must temporarily resurrect the
the object in much the same way that class instances are resurrected object in much the same way that class instances are resurrected
before their __del__ is called. before their __del__ is called.
Since ghost objects are stored under a different regime to Since ghost objects are stored under a different regime to non-ghost
non-ghost objects, an extra ghostify function in cPersistenceAPI objects, an extra ghostify function in cPersistenceAPI replaces
replaces self->state=GHOST_STATE assignments that were common in self->state=GHOST_STATE assignments that were common in other
other persistent classes (such as BTrees). persistent classes (such as BTrees).
Regime 3: Non-Ghost Objects Regime 3: Non-Ghost Objects
Non-ghost objects are stored in two data structures. Firstly, in Non-ghost objects are stored in two data structures. Firstly, in the
the dictionary along with everything else, with a *strong* reference. dictionary along with everything else, with a *strong* reference.
Secondly, they are stored in a doubly-linked-list which encodes Secondly, they are stored in a doubly-linked-list which encodes the
the order in which these objects have been most recently used. order in which these objects have been most recently used.
The doubly-link-list nodes contain next and previous pointers The doubly-link-list nodes contain next and previous pointers linking
linking together the cache and all non-ghost persistent objects. together the cache and all non-ghost persistent objects.
The node embedded in the cache is the home position. On every The node embedded in the cache is the home position. On every
attribute access a non-ghost object will relink itself just attribute access a non-ghost object will relink itself just behind the
behind the home position in the ring. Objects accessed least home position in the ring. Objects accessed least recently will
recently will eventually find themselves positioned after eventually find themselves positioned after the home position.
the home position.
Occasionally other nodes are temporarily inserted in the ring as
Occasionally other nodes are temporarily inserted in the ring position markers. The cache contains a ring_lock flag which must be
as position markers. The cache contains a ring_lock flag which set and unset before and after doing so. Only if the flag is unset can
must be set and unset before and after doing so. Only if the flag the cache assume that all nodes are either his own home node, or nodes
is unset can the cache assume that all nodes are either his own from persistent objects. This assumption is useful during the garbage
home node, or nodes from persistent objects. This assumption is collection process.
useful during the garbage collection process.
The number of non-ghost objects is counted in self->non_ghost_count. The number of non-ghost objects is counted in self->non_ghost_count.
The garbage collection process consists of traversing the ring, and The garbage collection process consists of traversing the ring, and
...@@ -80,17 +79,16 @@ deactivating (that is, turning into a ghost) every object until ...@@ -80,17 +79,16 @@ deactivating (that is, turning into a ghost) every object until
self->non_ghost_count is down to the target size, or until it self->non_ghost_count is down to the target size, or until it
reaches the home position again. reaches the home position again.
Note that objects in the sticky or changed states are still kept Note that objects in the sticky or changed states are still kept in
in the ring, however they can not be deactivated. The garbage the ring, however they can not be deactivated. The garbage collection
collection process must skip such objects, rather than deactivating process must skip such objects, rather than deactivating them.
them.
*/ */
static char cPickleCache_doc_string[] = static char cPickleCache_doc_string[] =
"Defines the PickleCache used by ZODB Connection objects.\n" "Defines the PickleCache used by ZODB Connection objects.\n"
"\n" "\n"
"$Id: cPickleCache.c,v 1.52 2002/04/03 17:20:33 htrd Exp $\n"; "$Id: cPickleCache.c,v 1.53 2002/04/03 17:53:27 jeremy Exp $\n";
#define ASSIGN(V,E) {PyObject *__e; __e=(E); Py_XDECREF(V); (V)=__e;} #define ASSIGN(V,E) {PyObject *__e; __e=(E); Py_XDECREF(V); (V)=__e;}
#define UNLESS(E) if(!(E)) #define UNLESS(E) if(!(E))
......
src/persistent/cPickleCache.c
View file @ deddffab
...@@ -21,58 +21,57 @@ Regime 1: Persistent Classes ...@@ -21,58 +21,57 @@ Regime 1: Persistent Classes
Persistent Classes are part of ZClasses. They are stored in the Persistent Classes are part of ZClasses. They are stored in the
self->data dictionary, and are never garbage collected. self->data dictionary, and are never garbage collected.
The klass_items() method returns a sequence of (oid,object) tuples The klass_items() method returns a sequence of (oid,object) tuples for
for every Persistent Class, which should make it possible to every Persistent Class, which should make it possible to implement
implement garbage collection in Python if necessary. garbage collection in Python if necessary.
Regime 2: Ghost Objects Regime 2: Ghost Objects
There is no benefit to keeping a ghost object which has no There is no benefit to keeping a ghost object which has no external
external references, therefore a weak reference scheme is references, therefore a weak reference scheme is used to ensure that
used to ensure that ghost objects are removed from memory ghost objects are removed from memory as soon as possible, when the
as soon as possible, when the last external reference is lost. last external reference is lost.
Ghost objects are stored in the self->data dictionary. Normally Ghost objects are stored in the self->data dictionary. Normally a
a dictionary keeps a strong reference on its values, however dictionary keeps a strong reference on its values, however this
this reference count is 'stolen'. reference count is 'stolen'.
This weak reference scheme leaves a dangling reference, in the This weak reference scheme leaves a dangling reference, in the
dictionary, when the last external reference is lost. To clean up dictionary, when the last external reference is lost. To clean up this
this dangling reference the persistent object dealloc function dangling reference the persistent object dealloc function calls
calls self->cache->_oid_unreferenced(self->oid). The cache looks self->cache->_oid_unreferenced(self->oid). The cache looks up the oid
up the oid in the dictionary, ensures it points to an object whose in the dictionary, ensures it points to an object whose reference
reference count is zero, then removes it from the dictionary. Before count is zero, then removes it from the dictionary. Before removing
removing the object from the dictionary it must temporarily resurrect the object from the dictionary it must temporarily resurrect the
the object in much the same way that class instances are resurrected object in much the same way that class instances are resurrected
before their __del__ is called. before their __del__ is called.
Since ghost objects are stored under a different regime to Since ghost objects are stored under a different regime to non-ghost
non-ghost objects, an extra ghostify function in cPersistenceAPI objects, an extra ghostify function in cPersistenceAPI replaces
replaces self->state=GHOST_STATE assignments that were common in self->state=GHOST_STATE assignments that were common in other
other persistent classes (such as BTrees). persistent classes (such as BTrees).
Regime 3: Non-Ghost Objects Regime 3: Non-Ghost Objects
Non-ghost objects are stored in two data structures. Firstly, in Non-ghost objects are stored in two data structures. Firstly, in the
the dictionary along with everything else, with a *strong* reference. dictionary along with everything else, with a *strong* reference.
Secondly, they are stored in a doubly-linked-list which encodes Secondly, they are stored in a doubly-linked-list which encodes the
the order in which these objects have been most recently used. order in which these objects have been most recently used.
The doubly-link-list nodes contain next and previous pointers The doubly-link-list nodes contain next and previous pointers linking
linking together the cache and all non-ghost persistent objects. together the cache and all non-ghost persistent objects.
The node embedded in the cache is the home position. On every The node embedded in the cache is the home position. On every
attribute access a non-ghost object will relink itself just attribute access a non-ghost object will relink itself just behind the
behind the home position in the ring. Objects accessed least home position in the ring. Objects accessed least recently will
recently will eventually find themselves positioned after eventually find themselves positioned after the home position.
the home position.
Occasionally other nodes are temporarily inserted in the ring as
Occasionally other nodes are temporarily inserted in the ring position markers. The cache contains a ring_lock flag which must be
as position markers. The cache contains a ring_lock flag which set and unset before and after doing so. Only if the flag is unset can
must be set and unset before and after doing so. Only if the flag the cache assume that all nodes are either his own home node, or nodes
is unset can the cache assume that all nodes are either his own from persistent objects. This assumption is useful during the garbage
home node, or nodes from persistent objects. This assumption is collection process.
useful during the garbage collection process.
The number of non-ghost objects is counted in self->non_ghost_count. The number of non-ghost objects is counted in self->non_ghost_count.
The garbage collection process consists of traversing the ring, and The garbage collection process consists of traversing the ring, and
...@@ -80,17 +79,16 @@ deactivating (that is, turning into a ghost) every object until ...@@ -80,17 +79,16 @@ deactivating (that is, turning into a ghost) every object until
self->non_ghost_count is down to the target size, or until it self->non_ghost_count is down to the target size, or until it
reaches the home position again. reaches the home position again.
Note that objects in the sticky or changed states are still kept Note that objects in the sticky or changed states are still kept in
in the ring, however they can not be deactivated. The garbage the ring, however they can not be deactivated. The garbage collection
collection process must skip such objects, rather than deactivating process must skip such objects, rather than deactivating them.
them.
*/ */
static char cPickleCache_doc_string[] = static char cPickleCache_doc_string[] =
"Defines the PickleCache used by ZODB Connection objects.\n" "Defines the PickleCache used by ZODB Connection objects.\n"
"\n" "\n"
"$Id: cPickleCache.c,v 1.52 2002/04/03 17:20:33 htrd Exp $\n"; "$Id: cPickleCache.c,v 1.53 2002/04/03 17:53:27 jeremy Exp $\n";
#define ASSIGN(V,E) {PyObject *__e; __e=(E); Py_XDECREF(V); (V)=__e;} #define ASSIGN(V,E) {PyObject *__e; __e=(E); Py_XDECREF(V); (V)=__e;}
#define UNLESS(E) if(!(E)) #define UNLESS(E) if(!(E))
......
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