From a6ec504513d751dff2b4b986b01891f94718477a Mon Sep 17 00:00:00 2001
From: Michael Carlberg <c@rlberg.se>
Date: Wed, 1 Jun 2016 01:07:23 +0200
Subject: [PATCH] feat(core): Throttle writes to stdout

---
 README.md             | 11 +++++++++++
 config                |  7 +++++++
 examples/config       |  7 +++++++
 examples/config.bspwm |  7 +++++++
 examples/config.i3    |  7 +++++++
 src/eventloop.cpp     | 36 ++++++++++++++++++++++++++++++++++--
 6 files changed, 73 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 1fecca61..2ae2a50f 100644
--- a/README.md
+++ b/README.md
@@ -160,6 +160,17 @@ the resulting output might not be award-winning.
 `🟊 = module is still flagged as work in progress`
 
 
+### Application settings
+  ~~~ ini
+  [settings]
+  ; Limit the amount of events sent to lemonbar within a set timeframe:
+  ; - "Allow <throttle_limit> updates within <throttle_ms> of time"
+  ; Default values:
+  ;throttle_limit = 5
+  ;throttle_ms = 50
+  ~~~
+
+
 ### Module `internal/backlight`
   ~~~ ini
   [module/backlight]
diff --git a/config b/config
index a37b014e..a23a08e1 100644
--- a/config
+++ b/config
@@ -1,3 +1,10 @@
+[settings]
+; Limit the amount of events sent to lemonbar within a set timeframe:
+; - "Allow <throttle_limit> updates within <throttle_ms> of time"
+; Default values:
+throttle_limit = 5
+throttle_ms = 50
+
 ;
 ; Bar configurations
 ; ---------------------------------------
diff --git a/examples/config b/examples/config
index 214ec69f..bd5adcab 100644
--- a/examples/config
+++ b/examples/config
@@ -1,3 +1,10 @@
+[settings]
+; Limit the amount of events sent to lemonbar within a set timeframe:
+; - "Allow <throttle_limit> updates within <throttle_ms> of time"
+; Default values:
+;throttle_limit = 5
+;throttle_ms = 50
+
 [bar/example]
 width = 100%
 height = 25
diff --git a/examples/config.bspwm b/examples/config.bspwm
index 0c7a915b..019611a6 100644
--- a/examples/config.bspwm
+++ b/examples/config.bspwm
@@ -1,3 +1,10 @@
+[settings]
+; Limit the amount of events sent to lemonbar within a set timeframe:
+; - "Allow <throttle_limit> updates within <throttle_ms> of time"
+; Default values:
+;throttle_limit = 5
+;throttle_ms = 50
+
 [bar/example]
 width = 100%
 height = 25
diff --git a/examples/config.i3 b/examples/config.i3
index 0043936a..7aa3d5f0 100644
--- a/examples/config.i3
+++ b/examples/config.i3
@@ -1,3 +1,10 @@
+[settings]
+; Limit the amount of events sent to lemonbar within a set timeframe:
+; - "Allow <throttle_limit> updates within <throttle_ms> of time"
+; Default values:
+;throttle_limit = 5
+;throttle_ms = 50
+
 [bar/example]
 width = 100%
 height = 25
diff --git a/src/eventloop.cpp b/src/eventloop.cpp
index 92f538cc..291a569e 100644
--- a/src/eventloop.cpp
+++ b/src/eventloop.cpp
@@ -3,6 +3,7 @@
 #include <stdlib.h>
 #include <fcntl.h>
 #include <sys/stat.h>
+#include <deque>
 
 #include "eventloop.hpp"
 #include "services/command.hpp"
@@ -98,10 +99,41 @@ void EventLoop::add_stdin_subscriber(const std::string& module_name)
 
 void EventLoop::loop_write()
 {
+  std::deque<std::chrono::high_resolution_clock::time_point> ticks;
+
+  // Allow <throttle_limit>  ticks within <throttle_ms> timeframe
+  const auto throttle_limit = config::get<unsigned int>("settings", "throttle_limit", 5);
+  const auto throttle_ms = std::chrono::duration<double, std::milli>(config::get<unsigned int>("settings", "throttle_ms", 50));
+
   while (this->running()) {
     try {
-      if (this->registry->wait())
-        this->write_stdout();
+      if (!this->registry->wait())
+        continue;
+
+      auto now = std::chrono::high_resolution_clock::now();
+
+      // Expire previous ticks
+      while (ticks.size() > 0) {
+        if ((now - ticks.front()) < throttle_ms)
+          break;
+
+        ticks.pop_front();
+      }
+
+      // Place the new tick in the bottom of the deck
+      ticks.emplace_back(std::chrono::high_resolution_clock::now());
+
+      // Have we reached the limit?
+      if (ticks.size() >= throttle_limit) {
+        log_debug("Throttling write to stdout");
+
+        std::this_thread::sleep_for(throttle_ms * ticks.size());
+
+        if (ticks.size() - 1 >= throttle_limit)
+          continue;
+      }
+
+      this->write_stdout();
     } catch (Exception &e) {
       this->logger->error(e.what());
       return;