From eea3a1ecd38bda7b942c621001705a79ac6024e3 Mon Sep 17 00:00:00 2001
From: gingerBill <bill@gingerbill.org>
Date: Mon, 9 Nov 2020 13:05:02 +0000
Subject: [PATCH] Improve sync.Channel to encode the direction into the type

---
 core/sync/channel.odin | 91 ++++++++++++++++++++++++++++--------------
 1 file changed, 60 insertions(+), 31 deletions(-)

diff --git a/core/sync/channel.odin b/core/sync/channel.odin
index 4259384ce..142c8f602 100644
--- a/core/sync/channel.odin
+++ b/core/sync/channel.odin
@@ -2,60 +2,89 @@ package sync
 
 import "core:mem"
 import "core:time"
-import "core:intrinsics"
+import "intrinsics"
 import "core:math/rand"
 
 _, _ :: time, rand;
 
+Channel_Direction :: enum i8 {
+	Both =  0,
+	Send = +1,
+	Recv = -1,
+}
 
-Channel :: struct(T: typeid) {
+Channel :: struct(T: typeid, Direction := Channel_Direction.Both) {
 	using _internal: ^Raw_Channel,
 }
 
-channel_init :: proc(ch: ^$C/Channel($T), cap := 0, allocator := context.allocator) {
+channel_init :: proc(ch: ^$C/Channel($T, $D), cap := 0, allocator := context.allocator) {
 	context.allocator = allocator;
 	ch._internal = raw_channel_create(size_of(T), align_of(T), cap);
 	return;
 }
 
-channel_make :: proc($T: typeid, cap := 0, allocator := context.allocator) -> (ch: Channel(T)) {
+channel_make :: proc($T: typeid, cap := 0, allocator := context.allocator) -> (ch: Channel(T, .Both)) {
 	context.allocator = allocator;
 	ch._internal = raw_channel_create(size_of(T), align_of(T), cap);
 	return;
 }
 
-channel_destroy :: proc(ch: $C/Channel($T)) {
+channel_make_send :: proc($T: typeid, cap := 0, allocator := context.allocator) -> (ch: Channel(T, .Send)) {
+	context.allocator = allocator;
+	ch._internal = raw_channel_create(size_of(T), align_of(T), cap);
+	return;
+}
+channel_make_recv :: proc($T: typeid, cap := 0, allocator := context.allocator) -> (ch: Channel(T, .Recv)) {
+	context.allocator = allocator;
+	ch._internal = raw_channel_create(size_of(T), align_of(T), cap);
+	return;
+}
+
+channel_destroy :: proc(ch: $C/Channel($T, $D)) {
 	raw_channel_destroy(ch._internal);
 }
 
-
-channel_len :: proc(ch: $C/Channel($T)) -> int {
-	return ch._internal.len;
+channel_as_send :: proc(ch: $C/Channel($T, .Both)) -> (res: Channel(T, .Send)) {
+	res._internal = ch._internal;
+	return;
 }
-channel_cap :: proc(ch: $C/Channel($T)) -> int {
-	return ch._internal.cap;
+
+channel_as_recv :: proc(ch: $C/Channel($T, .Both)) -> (res: Channel(T, .Recv)) {
+	res._internal = ch._internal;
+	return;
 }
 
 
-channel_send :: proc(ch: $C/Channel($T), msg: T, loc := #caller_location) {
+channel_len :: proc(ch: $C/Channel($T, $D)) -> int {
+	return ch._internal.len if ch._internal != nil else 0;
+}
+channel_cap :: proc(ch: $C/Channel($T, $D)) -> int {
+	return ch._internal.cap if ch._internal != nil else 0;
+}
+
+
+channel_send :: proc(ch: $C/Channel($T, $D), msg: T, loc := #caller_location) where D >= .Both {
 	msg := msg;
 	_ = raw_channel_send_impl(ch._internal, &msg, /*block*/true, loc);
 }
-channel_try_send :: proc(ch: $C/Channel($T), msg: T, loc := #caller_location) -> bool {
+channel_try_send :: proc(ch: $C/Channel($T, $D), msg: T, loc := #caller_location) -> bool where D >= .Both {
 	msg := msg;
 	return raw_channel_send_impl(ch._internal, &msg, /*block*/false, loc);
 }
 
-channel_recv :: proc(ch: $C/Channel($T), loc := #caller_location) -> (msg: T) {
+channel_recv :: proc(ch: $C/Channel($T, $D), loc := #caller_location) -> (msg: T) where D <= .Both {
 	c := ch._internal;
+	if c == nil {
+		panic(message="cannot recv message; channel is nil", loc=loc);
+	}
 	mutex_lock(&c.mutex);
 	raw_channel_recv_impl(c, &msg, loc);
 	mutex_unlock(&c.mutex);
 	return;
 }
-channel_try_recv :: proc(ch: $C/Channel($T), loc := #caller_location) -> (msg: T, ok: bool) {
+channel_try_recv :: proc(ch: $C/Channel($T, $D), loc := #caller_location) -> (msg: T, ok: bool) where D <= .Both {
 	c := ch._internal;
-	if mutex_try_lock(&c.mutex) {
+	if c != nil && mutex_try_lock(&c.mutex) {
 		if c.len > 0 {
 			raw_channel_recv_impl(c, &msg, loc);
 			ok = true;
@@ -64,7 +93,7 @@ channel_try_recv :: proc(ch: $C/Channel($T), loc := #caller_location) -> (msg: T
 	}
 	return;
 }
-channel_try_recv_ptr :: proc(ch: $C/Channel($T), msg: ^T, loc := #caller_location) -> (ok: bool) {
+channel_try_recv_ptr :: proc(ch: $C/Channel($T, $D), msg: ^T, loc := #caller_location) -> (ok: bool) where D <= .Both {
 	res: T;
 	res, ok = channel_try_recv(ch, loc);
 	if ok && msg != nil {
@@ -74,32 +103,32 @@ channel_try_recv_ptr :: proc(ch: $C/Channel($T), msg: ^T, loc := #caller_locatio
 }
 
 
-channel_is_nil :: proc(ch: $C/Channel($T)) -> bool {
+channel_is_nil :: proc(ch: $C/Channel($T, $D)) -> bool {
 	return ch._internal == nil;
 }
-channel_is_open :: proc(ch: $C/Channel($T)) -> bool {
+channel_is_open :: proc(ch: $C/Channel($T, $D)) -> bool {
 	c := ch._internal;
 	return c != nil && !c.closed;
 }
 
 
-channel_eq :: proc(a, b: $C/Channel($T)) -> bool {
+channel_eq :: proc(a, b: $C/Channel($T, $D)) -> bool {
 	return a._internal == b._internal;
 }
-channel_ne :: proc(a, b: $C/Channel($T)) -> bool {
+channel_ne :: proc(a, b: $C/Channel($T, $D)) -> bool {
 	return a._internal != b._internal;
 }
 
 
-channel_can_send :: proc(ch: $C/Channel($T)) -> (ok: bool) {
+channel_can_send :: proc(ch: $C/Channel($T, $D)) -> (ok: bool) where D >= .Both {
 	return raw_channel_can_send(ch._internal);
 }
-channel_can_recv :: proc(ch: $C/Channel($T)) -> (ok: bool) {
+channel_can_recv :: proc(ch: $C/Channel($T, $D)) -> (ok: bool) where D <= .Both {
 	return raw_channel_can_recv(ch._internal);
 }
 
 
-channel_peek :: proc(ch: $C/Channel($T)) -> int {
+channel_peek :: proc(ch: $C/Channel($T, $D)) -> int {
 	c := ch._internal;
 	if c == nil {
 		return -1;
@@ -111,12 +140,12 @@ channel_peek :: proc(ch: $C/Channel($T)) -> int {
 }
 
 
-channel_close :: proc(ch: $C/Channel($T), loc := #caller_location) {
+channel_close :: proc(ch: $C/Channel($T, $D), loc := #caller_location) {
 	raw_channel_close(ch._internal, loc);
 }
 
 
-channel_iterator :: proc(ch: $C/Channel($T)) -> (msg: T, ok: bool) {
+channel_iterator :: proc(ch: $C/Channel($T, $D)) -> (msg: T, ok: bool) where D >= .Both {
 	c := ch._internal;
 	if c == nil {
 		return;
@@ -127,12 +156,12 @@ channel_iterator :: proc(ch: $C/Channel($T)) -> (msg: T, ok: bool) {
 	}
 	return;
 }
-channel_drain :: proc(ch: $C/Channel($T)) {
+channel_drain :: proc(ch: $C/Channel($T, $D)) where D >= .Both {
 	raw_channel_drain(ch._internal);
 }
 
 
-channel_move :: proc(dst, src: $C/Channel($T)) {
+channel_move :: proc(dst: $C1/Channel($T, $D1) src: $C2/Channel(T, $D2)) where D1 <= .Both, D2 >= .Both {
 	for msg in channel_iterator(src) {
 		channel_send(dst, msg);
 	}
@@ -509,7 +538,7 @@ select_recv :: proc(channels: ..^Raw_Channel) -> (index: int) {
 	return;
 }
 
-select_recv_msg :: proc(channels: ..$C/Channel($T)) -> (msg: T, index: int) {
+select_recv_msg :: proc(channels: ..$C/Channel($T, $D)) -> (msg: T, index: int) {
 	switch len(channels) {
 	case 0:
 		panic("sync: select with no channels");
@@ -560,7 +589,7 @@ select_recv_msg :: proc(channels: ..$C/Channel($T)) -> (msg: T, index: int) {
 	return;
 }
 
-select_send_msg :: proc(msg: $T, channels: ..$C/Channel(T)) -> (index: int) {
+select_send_msg :: proc(msg: $T, channels: ..$C/Channel(T, $D)) -> (index: int) {
 	switch len(channels) {
 	case 0:
 		panic("sync: select with no channels");
@@ -781,7 +810,7 @@ select_try_send :: proc(channels: ..^Raw_Channel) -> (index: int) #no_bounds_che
 	return;
 }
 
-select_try_recv_msg :: proc(channels: ..$C/Channel($T)) -> (msg: T, index: int) {
+select_try_recv_msg :: proc(channels: ..$C/Channel($T, $D)) -> (msg: T, index: int) {
 	switch len(channels) {
 	case 0:
 		index = 0;
@@ -820,7 +849,7 @@ select_try_recv_msg :: proc(channels: ..$C/Channel($T)) -> (msg: T, index: int)
 	return;
 }
 
-select_try_send_msg :: proc(msg: $T, channels: ..$C/Channel(T)) -> (index: int) {
+select_try_send_msg :: proc(msg: $T, channels: ..$C/Channel(T, $D)) -> (index: int) {
 	switch len(channels) {
 	case 0:
 		index = 0;