[libj6] Make j6::thread a template for lambdas

Instead of a C-style function pointer taking `void *userdata`, let
j6::thread take a lambda as its thread procedure.

src/libraries/j6/include/j6/thread.hh

@@ -8,40 +8,75 @@
 
 #include <stddef.h>
 #include <stdint.h>
+#include <j6/flags.h>
+#include <j6/memutils.h>
 #include <j6/types.h>
+#include <j6/syscalls.h>
 
 namespace j6 {
 
+template <typename Proc>
 class thread
 {
 public:
-    using proc = void (*)(void *);
-
     /// Constructor. Create a thread and its stack space, but
     /// do not start executing the thread.
     /// \arg p           The function where the thread will begin execution
     /// \arg stack_top   The address where the top of this thread's stack should be mapped
-    thread(proc p, uintptr_t stack_top);
+    /// \arg stack_size  Size of the stack, in bytes (default 64KiB)
+    thread(Proc p, uintptr_t stack_top, size_t stack_size = 0x10000) :
+        m_stack {j6_handle_invalid},
+        m_thread {j6_handle_invalid},
+        m_stack_top {stack_top},
+        m_proc {p}
+    {
+        uintptr_t stack_base = stack_top - stack_size;
+        m_status = j6_vma_create_map(&m_stack, stack_size, stack_base, j6_vm_flag_write);
+        if (m_status != j6_status_ok)
+            return;
+
+        static constexpr size_t zeros_size = 0x10;
+        m_stack_top -= zeros_size; // Sentinel
+        memset(reinterpret_cast<void*>(m_stack_top), 0, zeros_size);
+    }
 
     /// Start executing the thread.
-    /// \arg user  Optional pointer to user data to pass to the thread proc
     /// \returns   j6_status_ok if the thread was successfully started.
-    j6_status_t start(void *user = nullptr);
+    j6_status_t start()
+    {
+        if (m_status != j6_status_ok)
+            return m_status;
+
+        if (m_thread != j6_handle_invalid)
+            return j6_err_invalid_arg;
+
+        uint64_t arg0 = reinterpret_cast<uint64_t>(this);
+
+        m_status = j6_thread_create(&m_thread, 0,
+            m_stack_top, reinterpret_cast<uintptr_t>(init_proc),
+            arg0, 0);
+
+        return m_status;
+    }
 
     /// Wait for the thread to stop executing.
-    void join();
+    void join() { j6_thread_join(m_thread); }
 
     thread() = delete;
     thread(const thread&) = delete;
 
 private:
-    static void init_proc(thread *t, void *user);
+    static void init_proc(thread *t)
+    {
+        t->m_proc();
+        j6_thread_exit();
+    }
 
     j6_status_t m_status;
     j6_handle_t m_stack;
     j6_handle_t m_thread;
     uintptr_t m_stack_top;
-    proc m_proc;
+    Proc m_proc;
 };
 
 } // namespace j6

src/libraries/j6/j6.module

@@ -15,7 +15,6 @@ j6 = module("j6",
         "syscalls.s.cog",
         "sysconf.cpp.cog",
         "syslog.cpp",
-        "thread.cpp",
     ],
     public_headers = [
         "j6/cap_flags.h.cog",

src/libraries/j6/thread.cpp

@@ -1,65 +0,0 @@
-// The kernel depends on libj6 for some shared code,
-// but should not include the user-specific code.
-#ifndef __j6kernel
-
-#include <j6/errors.h>
-#include <j6/flags.h>
-#include <j6/memutils.h>
-#include <j6/syscalls.h>
-#include <j6/thread.hh>
-
-namespace j6 {
-
-static constexpr size_t stack_size = 0x10000;
-static constexpr size_t zeros_size = 0x10;
-
-thread::thread(thread::proc p, uintptr_t stack_top) :
-    m_stack {j6_handle_invalid},
-    m_thread {j6_handle_invalid},
-    m_stack_top {stack_top},
-    m_proc {p}
-{
-    uintptr_t stack_base = stack_top - stack_size;
-    m_status = j6_vma_create_map(&m_stack, stack_size, stack_base, j6_vm_flag_write);
-    if (m_status != j6_status_ok)
-        return;
-
-    m_stack_top -= zeros_size;
-    memset(reinterpret_cast<void*>(m_stack_top), 0, zeros_size);
-}
-
-j6_status_t
-thread::start(void *user)
-{
-    if (m_status != j6_status_ok)
-        return m_status;
-
-    if (m_thread != j6_handle_invalid)
-        return j6_err_invalid_arg;
-
-    uint64_t arg0 = reinterpret_cast<uint64_t>(this);
-    uint64_t arg1 = reinterpret_cast<uint64_t>(user);
-
-    m_status = j6_thread_create(&m_thread, 0,
-        m_stack_top, reinterpret_cast<uintptr_t>(init_proc),
-        arg0, arg1);
-
-    return m_status;
-}
-
-void
-thread::join()
-{
-    j6_thread_join(m_thread);
-}
-
-void
-thread::init_proc(thread *t, void *user)
-{
-    t->m_proc(user);
-    j6_thread_exit();
-}
-
-} // namespace j6
-
-#endif // __j6kernel

src/user/testapp/main.cpp

@@ -111,8 +111,8 @@ main(int argc, const char **argv)
 
     j6_log("main thread created channel");
 
-    j6::thread child_thread {thread_proc, stack_top};
+    j6::thread child_thread {[=](){ thread_proc(chan); }, stack_top};
-    j6_status_t result = child_thread.start(chan);
+    j6_status_t result = child_thread.start();
     if (result != j6_status_ok)
         return result;