Changeset baed175 in mainline

Timestamp:

2018-07-05T21:41:23Z (6 years ago)

Author:

Dzejrou <dzejrou@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

09e02ee

Parents:

db54a9d

git-author:

Dzejrou <dzejrou@…> (2018-05-09 23:06:44)

git-committer:

Dzejrou <dzejrou@…> (2018-07-05 21:41:23)

Message:

cpp: added weak_ptr

Location:

uspace/lib/cpp/include/internal/memory

Files:

• shared_payload.hpp (modified) (3 diffs)
• shared_ptr.hpp (modified) (2 diffs)
• weak_ptr.hpp (added)

uspace/lib/cpp/include/internal/memory/shared_payload.hpp

@@ -72 +72 @@
             virtual refcount_t weak_refs() const noexcept = 0;
             virtual bool expired() const noexcept = 0;
+            virtual shared_payload_base* lock() noexcept = 0;
 
             virtual ~shared_payload_base() = default;
@@ -145 +146 @@
             {
                 if (__atomic_sub_fetch(&refcount_, 1, __ATOMIC_ACQ_REL) == 0)
-                    return decrement_weak();
+                {
+                    /**
+                     * First call to destroy() will delete the held object,
+                     * so it doesn't matter what the weak_refcount_ is,
+                     * but we added one and we need to remove it now.
+                     */
+                    decrement_weak();
+
+                    return true;
+                }
                 else
                     return false;
@@ -168 +178 @@
             {
                 return refs() == 0;
+            }
+
+            shared_payload_base<T>* lock() noexcept override
+            {
+                refcount_t rfs = refs();
+                while (rfs != 0L)
+                {
+                    if (__atomic_compare_exchange_n(&refcount_, &rfs, rfs + 1,
+                                                    true, __ATOMIC_RELAXED,
+                                                    __ATOMIC_RELAXED))
+                    {
+                        return this;
+                    }
+                }
+
+                return nullptr;
             }
 

uspace/lib/cpp/include/internal/memory/shared_ptr.hpp

@@ -31 +31 @@
 
 #include <exception>
-#include <functional>
+#include <internal/functional/arithmetic_operations.hpp>
 #include <internal/memory/allocator_arg.hpp>
 #include <internal/memory/shared_payload.hpp>
@@ -333 +333 @@
             {
                 if (payload_)
-                    return payload_->refcount();
+                    return payload_->refs();
                 else
                     return 0L;