[util] Add util::deque container

Adding the util::deque container, implemented with the util::linked_list
of arrays of items.

Also, use the deque for a kobject's blocked thread list to maintain
order instead of a vector using remove_swap().

src/kernel/objects/handle.h

@@ -23,6 +23,8 @@ struct handle
             static_cast<j6_handle_t>(obj ? obj->get_type() : kobject::type::none) << type_shift;
     }
 
+    inline handle() : id {j6_handle_invalid}, object {nullptr} {}
+
     inline handle(j6_handle_t in_id, kobject *in_obj, j6_cap_t caps) :
         id {make_id(in_id, caps, in_obj)}, object {in_obj} {
         if (object) object->handle_retain();
@@ -90,6 +92,7 @@ struct handle
     inline const kobject * as<kobject>() const { return object; }
 
     j6_handle_t id;
+    uint64_t badge;
     kobject *object;
 };
 

src/kernel/objects/kobject.cpp

@@ -37,32 +37,69 @@ kobject::koid_type(j6_koid_t koid)
     return static_cast<type>((koid >> 48) & 0xffffull);
 }
 
-void
+j6_signal_t
 kobject::assert_signal(j6_signal_t s)
 {
-    m_signals |= s;
+    j6_signal_t old =
+        __atomic_fetch_or(&m_signals, s, __ATOMIC_SEQ_CST);
     notify_signal_observers();
+    return old;
+}
+
+j6_signal_t
+kobject::deassert_signal(j6_signal_t s)
+{
+    return __atomic_fetch_and(&m_signals, ~s, __ATOMIC_SEQ_CST);
 }
 
 void
-kobject::deassert_signal(j6_signal_t s)
+kobject::compact_blocked_threads()
 {
-    m_signals &= ~s;
+    // Clean up what we can of the list
+    while (!m_blocked_threads.empty() && !m_blocked_threads.first())
+        m_blocked_threads.pop_front();
+    while (!m_blocked_threads.empty() && !m_blocked_threads.last())
+        m_blocked_threads.pop_back();
 }
 
 void
 kobject::notify_signal_observers()
 {
-    size_t i = 0;
-    while (i < m_blocked_threads.count()) {
-        thread *t = m_blocked_threads[i];
+    for (auto &entry : m_blocked_threads) {
+        if (entry == nullptr) continue;
+        if (entry->wake_on_signals(this, m_signals))
+            entry = nullptr;
+    }
+    compact_blocked_threads();
+}
 
-        if (t->wake_on_signals(this, m_signals)) {
-            m_blocked_threads.remove_swap_at(i);
-        } else {
-            ++i;
+void
+kobject::notify_object_observers(size_t count)
+{
+    if (!count) return;
+
+    for (auto &entry : m_blocked_threads) {
+        if (entry == nullptr) continue;
+        if (entry->wake_on_object(this)) {
+            entry = nullptr;
+            if (--count) break;
         }
     }
+    compact_blocked_threads();
+}
+
+void
+kobject::remove_blocked_thread(thread *t)
+{
+    // Can't really remove from a deque, so just
+    // null out removed entries.
+    for (auto &entry : m_blocked_threads) {
+        if (entry == t) {
+            entry = nullptr;
+            break;
+        }
+    }
+    compact_blocked_threads();
 }
 
 void

src/kernel/objects/kobject.h

@@ -5,7 +5,7 @@
 #include <j6/errors.h>
 #include <j6/signals.h>
 #include <j6/types.h>
-#include <util/vector.h>
+#include <util/deque.h>
 
 namespace obj {
 
@@ -46,11 +46,13 @@ public:
 
     /// Set the given signals active on this object
     /// \arg s    The set of signals to assert
-    void assert_signal(j6_signal_t s);
+    /// \returns  The previous state of the signals
+    j6_signal_t assert_signal(j6_signal_t s);
 
     /// Clear the given signals on this object
     /// \arg s    The set of signals to deassert
-    void deassert_signal(j6_signal_t s);
+    /// \returns  The previous state of the signals
+    j6_signal_t deassert_signal(j6_signal_t s);
 
     /// Check if the given signals are set on this object
     /// \arg s  The set of signals to check
@@ -68,10 +70,10 @@ public:
     }
 
     /// Add the given thread to the list of threads waiting on this object.
-    inline void add_blocked_thread(thread *t) { m_blocked_threads.append(t); }
+    inline void add_blocked_thread(thread *t) { m_blocked_threads.push_back(t); }
 
     /// Remove the given thread from the list of threads waiting on this object.
-    inline void remove_blocked_thread(thread *t) { m_blocked_threads.remove_swap(t); }
+    void remove_blocked_thread(thread *t);
 
     /// Perform any cleanup actions necessary to mark this object closed
     virtual void close();
@@ -93,12 +95,19 @@ private:
     /// \arg result  The result to pass to the observers
     void notify_signal_observers();
 
+    /// Compact the blocked threads deque
+    void compact_blocked_threads();
+
     j6_koid_t m_koid;
     j6_signal_t m_signals;
     uint16_t m_handle_count;
 
 protected:
-    util::vector<thread*> m_blocked_threads;
+    /// Notify threads waiting on this object
+    /// \arg count  Number of observers to wake, or -1ull for all
+    void notify_object_observers(size_t count = -1ull);
+
+    util::deque<thread*, 8> m_blocked_threads;
 };
 
 } // namespace obj

src/libraries/util/include/util/deque.h

@@ -0,0 +1,114 @@
+#pragma once
+/// \file linked_list.h
+/// A generic templatized linked list.
+
+#include <assert.h>
+#include <util/linked_list.h>
+
+namespace util {
+
+template <typename T, unsigned N = 16>
+class deque
+{
+    struct node { T items[N]; };
+    using list_type = linked_list<node>;
+    using node_type = typename list_type::item_type;
+
+public:
+    class iterator
+    {
+    public:
+        iterator(node_type *n, size_t i) : node(n), index(i) {}
+        iterator(const iterator &o) : node(o.node), index(o.index) {}
+        inline T& operator*() { assert(node); return node->items[index]; }
+        inline iterator & operator++() { incr(); return *this; }
+        inline iterator & operator++(int) { iterator old {*this}; incr(); return old; }
+        inline bool operator!=(const iterator &o) const { return !(*this == o); }
+        inline bool operator==(const iterator &o) const {
+            if (!node && !o.node) return true;
+            return index == o.index && node == o.node;
+        }
+    private:
+        void incr() { if (++index >= N) { index = 0; node = node->next(); }}
+        node_type *node;
+        size_t index;
+    };
+
+    deque() : m_first(0), m_next(N) {}
+    ~deque() {
+        while (!m_list.empty())
+            delete m_list.pop_front();
+    }
+
+    inline void push_front(const T& item) {
+        if (!m_first) { // need a new block at the start
+            m_list.push_front(new node_type);
+            m_first = N;
+        }
+        m_list.front()->items[--m_first] = item;
+    }
+
+    inline void push_back(const T& item) {
+        if (m_next == N) { // need a new block at the end
+            m_list.push_back(new node_type);
+            m_next = 0;
+        }
+        m_list.back()->items[m_next++] = item;
+    }
+
+    inline T pop_front() {
+        assert(!empty() && "Calling pop_front() on an empty deque");
+        T value = m_list.front()->items[m_first++];
+        if (m_first == N) {
+            delete m_list.pop_front();
+            m_first = 0;
+            if (m_list.empty())
+                m_next = N;
+        }
+        return value;
+    }
+
+    inline T pop_back() {
+        assert(!empty() && "Calling pop_back() on an empty deque");
+        T value = m_list.back()->items[--m_next];
+        if (m_next == 0) {
+            delete m_list.pop_back();
+            m_next = N;
+            if (m_list.empty())
+                m_first = 0;
+        }
+        return value;
+    }
+
+    inline bool empty() const { return m_list.empty(); }
+
+    inline T& first() {
+        assert(!empty() && "Calling first() on an empty deque");
+        return m_list.front()->items[m_first];
+    }
+
+    inline const T& first() const {
+        assert(!empty() && "Calling first() on an empty deque");
+        return m_list.front()->items[m_first];
+    }
+
+    inline T& last() {
+        assert(!empty() && "Calling last() on an empty deque");
+        return m_list.back()->items[m_next-1];
+    }
+
+    inline const T& last() const {
+        assert(!empty() && "Calling last() on an empty deque");
+        return m_list.back()->items[m_next-1];
+    }
+
+    iterator begin() { return iterator {m_list.front(), m_first}; }
+    iterator end() { return iterator {m_list.back(), m_next}; }
+
+private:
+    unsigned m_first; // Index of the first item in the first node
+    unsigned m_next;  // Index of the first empty item in the last node
+    list_type m_list;
+};
+
+} // namespace util