Allow manual cypclass locking and basic lock bookkeeping

Cython/Compiler/ExprNodes.py

@@ -721,6 +721,20 @@ class ExprNode(Node):
     def addr_not_const(self):
         error(self.pos, "Address is not constant")
 
+    def is_rhs_locked(self):
+        return True
+
+    def is_lhs_locked(self):
+        return True
+
+    def check_rhs_locked(self):
+        if not self.is_rhs_locked():
+            error(self.pos, "This rhs is not correctly locked (write lock for non-const methods, read lock is sufficient for everything else)")
+
+    def check_lhs_locked(self):
+        if not self.is_lhs_locked():
+            error(self.pos, "This lhs is not correctly locked (write lock needed)")
+
     # ----------------- Result Allocation -----------------
 
     def result_in_temp(self):
@@ -5983,6 +5997,9 @@ class SimpleCallNode(CallNode):
 
         self.overflowcheck = env.directives['overflowcheck']
 
+    def is_rhs_locked(self):
+        return self.function.is_rhs_locked()
+
     def calculate_result_code(self):
         return self.c_call_code()
 
@@ -7281,6 +7298,22 @@ class AttributeNode(ExprNode):
 
     gil_message = "Accessing Python attribute"
 
+    def is_rhs_locked(self):
+        # TODO: some chaining
+        obj = self.obj
+        if hasattr(obj, 'entry') and obj.entry.type.is_cyp_class and (obj.entry.is_variable or obj.entry.is_cfunction)\
+           and not (obj.entry.is_rlocked and (not self.entry.is_cfunction or self.entry.type.is_const_method) or obj.entry.is_wlocked):
+            return False
+        return True
+
+    def is_lhs_locked(self):
+        # TODO: some chaining
+        obj = self.obj
+        if self.is_lvalue() and hasattr(obj, 'entry') and obj.entry.type.is_cyp_class and not obj.entry.is_wlocked:
+            return False
+        return True
+
+
     def is_cimported_module_without_shadow(self, env):
         return self.obj.is_cimported_module_without_shadow(env)
 

Cython/Compiler/Nodes.py

@@ -5590,6 +5590,7 @@ class ExprStatNode(StatNode):
     def analyse_expressions(self, env):
         self.expr.result_is_used = False  # hint that .result() may safely be left empty
         self.expr = self.expr.analyse_expressions(env)
+        self.expr.check_rhs_locked()
         # Repeat in case of node replacement.
         self.expr.result_is_used = False  # hint that .result() may safely be left empty
         return self
@@ -5757,6 +5758,8 @@ class SingleAssignmentNode(AssignmentNode):
 
         self.lhs = self.lhs.analyse_target_types(env)
         self.lhs.gil_assignment_check(env)
+        self.rhs.check_rhs_locked()
+        self.lhs.check_lhs_locked()
         unrolled_assignment = self.unroll_lhs(env)
         if unrolled_assignment:
             return unrolled_assignment
@@ -8367,6 +8370,84 @@ class EnsureGILNode(GILExitNode):
     def generate_execution_code(self, code):
         code.put_ensure_gil(declare_gilstate=False)
 
+class LockCypclassNode(StatNode):
+    #  'with locked [cypclass object]' or 'with unlocked [cypclass object]' statement
+    #
+    #   state   string   'locked' or 'unlocked'
+    #   obj     ExprNode the (un)locked object
+    #   body    StatNode
+
+    child_attrs = ["body", "obj"]
+
+    def analyse_declarations(self, env):
+        self.body.analyse_declarations(env)
+        self.obj.analyse_declarations(env)
+
+    def analyse_expressions(self, env):
+        self.obj = self.obj.analyse_types(env)
+        if not hasattr(self.obj, 'entry'):
+            error(self.pos, "The (un)locking target has no entry")
+        if not self.obj.type.is_cyp_class:
+            error(self.pos, "Cannot (un)lock a non-cypclass variable !")
+
+        is_rlocked = self.obj.entry.is_rlocked
+        is_wlocked = self.obj.entry.is_wlocked
+
+        if self.state == "unclocked" and not (is_rlocked or is_wlocked):
+            error(self.pos, "Cannot unlock an already unlocked object !")
+
+        elif self.state == "rlocked" and is_rlocked:
+            error(self.pos, "Double read lock !")
+
+        elif self.state == "wlocked" and is_wlocked:
+            error(self.pos, "Double write lock !")
+
+
+        # We need to save states because in case of 'with unlocked' statement,
+        # we must know which lock has to be restored after the with body.
+        self.was_rlocked = is_rlocked
+        self.was_wlocked = is_wlocked
+
+        if self.state == "rlocked":
+            self.obj.entry.is_rlocked = True
+            self.obj.entry.is_wlocked = False
+        elif self.state == "wlocked":
+            self.obj.entry.is_rlocked = False
+            self.obj.entry.is_wlocked = True
+        else:
+            self.obj.entry.is_rlocked = False
+            self.obj.entry.is_wlocked = False
+
+        self.body = self.body.analyse_expressions(env)
+
+        self.obj.entry.is_rlocked = self.was_rlocked
+        self.obj.entry.is_wlocked = self.was_wlocked
+        return self
+
+    def generate_execution_code(self, code):
+        # We must unlock if it's a 'with unlocked' statement,
+        # or if we're changing lock type.
+        if self.was_rlocked or self.was_wlocked:
+            code.putln("Cy_UNLOCK(%s);" % self.obj.result())
+
+        # Then, lock accordingly
+        if self.state == "rlocked":
+            code.putln("Cy_RLOCK(%s);" % self.obj.result())
+        elif self.state == "wlocked":
+            code.putln("Cy_WLOCK(%s);" % self.obj.result())
+
+        self.body.generate_execution_code(code)
+
+        # We must unlock if we held a lock previously
+        if self.state != "unlocked":
+            code.putln("Cy_UNLOCK(%s);" % self.obj.result())
+
+        # Then, relock if needed
+        if self.was_rlocked:
+            code.putln("Cy_RLOCK(%s);" % self.obj.result())
+        elif self.was_wlocked:
+            code.putln("Cy_WLOCK(%s);" % self.obj.result())
+
 
 def cython_view_utility_code():
     from . import MemoryView

Cython/Compiler/Parsing.py

@@ -2066,6 +2066,20 @@ def p_with_items(s, is_async=False):
         else:
             body = p_suite(s)
         return Nodes.GILStatNode(pos, state=state, body=body, condition=condition)
+    elif not s.in_python_file and s.sy == 'IDENT' and s.systring in ('unlocked', 'rlocked', 'wlocked'):
+        state = s.systring
+        s.next()
+
+        if s.sy != 'IDENT':
+            s.error("The with %s statement must be followed by the cypclass object to operate on" % state, pos)
+
+        obj = p_starred_expr(s)
+        if s.sy == ',':
+            s.next()
+            body = p_with_items(s, is_async=is_async)
+        else:
+            body = p_suite(s)
+        return Nodes.LockCypclassNode(pos, state=state, obj=obj, body=body)
     else:
         manager = p_test(s)
         target = None

Cython/Compiler/Symtab.py

@@ -158,6 +158,8 @@ class Entry(object):
     # is_fused_specialized boolean Whether this entry of a cdef or def function
     #                              is a specialization
     # is_cgetter       boolean    Is a c-level getter function
+    # is_wlocked       boolean    Is locked with a write lock (used for cypclass)
+    # is_rlocked       boolean    Is locked with a read lock (used for cypclass)
 
     # TODO: utility_code and utility_code_definition serves the same purpose...
 
@@ -229,6 +231,8 @@ class Entry(object):
     cf_used = True
     outer_entry = None
     is_cgetter = False
+    is_wlocked = False
+    is_rlocked = False
 
     def __init__(self, name, cname, type, pos = None, init = None):
         self.name = name