feat(script): Configurable condition using exec-if

Add new config parameter `exec-if = cmd` that needs to
exit successfully before the main exec command will be invoked.

Closes #298

include/modules/cmdscript.hpp

@@ -11,6 +11,7 @@ namespace modules {
 
    protected:
     void process();
+    chrono::duration<double> sleep_duration();
   };
 }
 

include/modules/script.hpp

@@ -20,6 +20,7 @@ namespace modules {
 
    protected:
     virtual void process() = 0;
+    virtual chrono::duration<double> sleep_duration() = 0;
 
     static constexpr const char* TAG_OUTPUT{"<output>"};
     static constexpr const char* TAG_LABEL{"<label>"};
@@ -27,6 +28,8 @@ namespace modules {
     unique_ptr<command> m_command;
 
     string m_exec;
+    string m_exec_if;
+
     chrono::duration<double> m_interval{0};
     map<mousebtn, string> m_actions;
 

include/modules/tailscript.hpp

@@ -11,6 +11,7 @@ namespace modules {
 
    protected:
     void process();
+    chrono::duration<double> sleep_duration();
   };
 }
 

src/modules/cmdscript.cpp

@@ -11,12 +11,7 @@ namespace modules {
   }
 
   void cmdscript_module::process() {
-    if (!m_updatelock.try_lock()) {
-      return;
-    }
-
     try {
-      std::unique_lock<mutex> guard(m_updatelock, std::adopt_lock);
       auto exec = string_util::replace_all(m_exec, "%counter%", to_string(++m_counter));
       m_log.info("%s: Invoking shell command: \"%s\"", name(), exec);
       m_command = command_util::make_command(exec);
@@ -30,8 +25,10 @@ namespace modules {
       broadcast();
       m_prev = m_output;
     }
+  }
 
-    sleep(std::max(m_command->get_exit_status() == 0 ? m_interval : 1s, m_interval));
+  chrono::duration<double> cmdscript_module::sleep_duration() {
+    return std::max(m_command->get_exit_status() == 0 ? m_interval : 1s, m_interval);
   }
 }
 

src/modules/script.cpp

@@ -10,6 +10,7 @@ namespace modules {
 
   script_module::script_module(const bar_settings& bar, string name_) : module<script_module>(bar, move(name_)) {
     m_exec = m_conf.get(name(), "exec", m_exec);
+    m_exec_if = m_conf.get(name(), "exec-if", m_exec_if);
     m_maxlen = m_conf.get(name(), "maxlen", m_maxlen);
     m_ellipsis = m_conf.get(name(), "ellipsis", m_ellipsis);
     m_interval = m_conf.get<decltype(m_interval)>(name(), "interval", 5s);
@@ -36,7 +37,25 @@ namespace modules {
     m_mainthread = thread([this] {
       try {
         while (running() && !m_stopping) {
-          this->process();
+          std::unique_lock<mutex> guard(m_updatelock);
+
+          // Execute the condition command if specified
+          if (!m_exec_if.empty() && command_util::make_command(m_exec_if)->exec(true) != 0) {
+            if (!m_output.empty()) {
+              broadcast();
+              m_output.clear();
+              m_prev.clear();
+            }
+
+            if (m_interval >= 1s) {
+              sleep(m_interval);
+            } else {
+              sleep(1s);
+            }
+          } else {
+            this->process();
+            this->sleep(this->sleep_duration());
+          }
         }
       } catch (const exception& err) {
         halt(err.what());
@@ -62,7 +81,7 @@ namespace modules {
 
   string script_module::get_output() {
     if (m_output.empty()) {
-      return " ";
+      return "";
     }
 
     if (m_label) {

src/modules/tailscript.cpp

@@ -11,12 +11,6 @@ namespace modules {
   }
 
   void tailscript_module::process() {
-    if (!m_updatelock.try_lock()) {
-      return;
-    }
-
-    std::unique_lock<mutex> guard(m_updatelock, std::adopt_lock);
-
     if (!m_command || !m_command->is_running()) {
       string exec{string_util::replace_all(m_exec, "%counter%", to_string(++m_counter))};
       m_log.info("%s: Invoking shell command: \"%s\"", name(), exec);
@@ -36,13 +30,13 @@ namespace modules {
         broadcast();
       }
     }
+  }
 
-    guard.unlock();
+  chrono::duration<double> tailscript_module::sleep_duration() {
-
     if (m_command && !m_command->is_running()) {
-      sleep(std::max(m_command->get_exit_status() == 0 ? m_interval : 1s, m_interval));
+      return std::max(m_command->get_exit_status() == 0 ? m_interval : 1s, m_interval);
     } else {
-      sleep(m_interval);
+      return m_interval;
     }
   }
 }