use channel wait in geyser + fix retransmitShreds comment

src/geyser/core.zig

@@ -153,7 +153,9 @@ pub const GeyserWriter = struct {
     }
 
     pub fn IOStreamLoop(self: *Self) !void {
-        while (!self.exit.load(.acquire)) {
+        while (true) {
+            self.io_channel.waitToReceive(.{ .unordered = self.exit }) catch break;
+
             while (self.io_channel.tryReceive()) |payload| {
                 _ = self.writeToPipe(payload) catch |err| {
                     if (err == WritePipeError.PipeBlockedWithExitSignaled) {

src/geyser/main.zig

@@ -311,7 +311,9 @@ pub fn csvDumpIOWriter(
     var timer = try sig.time.Timer.start();
     errdefer exit.store(true, .monotonic);
 
-    while (!exit.load(.monotonic)) {
+    while (true) {
+        io_channel.waitToReceive(.{ .unordered = exit }) catch break;
+
         while (io_channel.tryReceive()) |csv_row| {
             // write to file
             try csv_file.writeAll(csv_row);

src/shred_network/shred_retransmitter.zig

@@ -323,7 +323,8 @@ fn retransmitShreds(
     while (!exit.load(.acquire)) {
         var retransmit_shred_timer = try sig.time.Timer.start();
 
-        // NOTE: multiple `retransmitShreds` run concurrently can't use receiver.wait() here.
+        // NOTE: multiple `retransmitShreds` run concurrently so we can't use
+        // `receiver.waitToReceive()` here as it only supports one caller thread.
         const retransmit_info: RetransmitShredInfo = receiver.tryReceive() orelse continue;
         defer retransmit_info.turbine_tree.releaseUnsafe();