add algo for mutating shared object

1 files changed, 41 insertions, 0 deletions

diff --git a/docs/application/shared.md b/docs/application/shared.md
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+# Shared
+
+---
+
+## Object Definition
+
+```c
+typedef struct _kpl_shared {
+    POOL_HEADER(_kpl_shared);
+    _Atomic bool mutating;
+    bool mark;
+    kpl_class class;
+    kpl_task *queue_head, queue_tail;
+    pthread_spinlock_t lock;
+} kpl_shared;
+
+static _Atomic int32_t shared_threads;
+
+static pthread_mutex_t shared_head_mutex;
+
+static kpl_shared *shared_head_sweep, *shared_head;
+```
+
+## Tracing
+
+1. Once triggered add a init task to the async queue
+2. This task moves the `shared_head` to the `shared_head_sweep` and sets the `shared_wait` to off for each thread
+3. Each thread will run down its queue queue marking found shared objects
+3. Once all have run and `shared_threads == available_threads` add a mark and sweep task to the async queue
+4. The async queue is moved to a temp queue and as each item on the tmep queue is marked it is moved back to the async queue
+5. A sweep on the `shared_head_sweep` is done
+6. What remains on the `shared_head_sweep` is added to `shared_head`
+
+## Mutating
+
+1. Check if state of `mutating`
+    1. If false, set to true and add the task to the `async_queue_head`
+    2. Once complete lock `lock` and check the `queue_head`
+    3. If empty set the state of `mutating` to false
+    4. Else queue the next task
+2. If the state of `mutating` is true add the task to `queue_tail`