logcatd: fix bug: subsequent reads after the first always return empty (#19994)

* refactor logcatd

* cleanup

* rename logger_list to loggers

* apply review

* little cleaner

Co-authored-by: Adeeb Shihadeh <adeebshihadeh@gmail.com>
old-commit-hash: 1b140bdbca

selfdrive/logcatd/logcatd_android.cc

@@ -1,54 +1,40 @@
-#include <unistd.h>
-#include <cstdio>
-#include <cstdlib>
-#include <cassert>
-#include <csignal>
-#include <cerrno>
-
 #include <android/log.h>
 #include <log/logger.h>
 #include <log/logprint.h>
 
-#include "common/timing.h"
 #include "common/util.h"
 #include "messaging.hpp"
 
+#define LOG_ID_KERNEL (log_id_t)5
 
 int main() {
   ExitHandler do_exit;
-
+  log_time last_log_time = {};
-  // setup android logging
-  struct logger_list *logger_list = android_logger_list_alloc(ANDROID_LOG_RDONLY, 0, 0);
-  assert(logger_list);
-  struct logger *main_logger = android_logger_open(logger_list, LOG_ID_MAIN);
-  assert(main_logger);
-  struct logger *radio_logger = android_logger_open(logger_list, LOG_ID_RADIO);
-  assert(radio_logger);
-  struct logger *system_logger = android_logger_open(logger_list, LOG_ID_SYSTEM);
-  assert(system_logger);
-  struct logger *crash_logger = android_logger_open(logger_list, LOG_ID_CRASH);
-  assert(crash_logger);
-  struct logger *kernel_logger = android_logger_open(logger_list, (log_id_t)5); // LOG_ID_KERNEL
-  assert(kernel_logger);
 
   PubMaster pm({"androidLog"});
+  while (!do_exit) {
+    // setup android logging
+    logger_list *loggers = last_log_time.tv_sec == 0 ?
+                           android_logger_list_alloc(ANDROID_LOG_RDONLY | ANDROID_LOG_NONBLOCK, 0, 0) :
+                           android_logger_list_alloc_time(ANDROID_LOG_RDONLY | ANDROID_LOG_NONBLOCK, last_log_time, 0);
+    assert(loggers);
+
+    const log_id_t log_ids[] = {LOG_ID_MAIN, LOG_ID_RADIO, LOG_ID_SYSTEM, LOG_ID_CRASH, LOG_ID_KERNEL};
+    for (const auto &id : log_ids) {
+      struct logger *log = android_logger_open(loggers, id);
+      assert(log != nullptr);
+    }
 
     while (!do_exit) {
       log_msg log_msg;
-    int err = android_logger_list_read(logger_list, &log_msg);
+      int err = android_logger_list_read(loggers, &log_msg);
-
+      if (err <= 0) break;
-    if (err == -EAGAIN) {
-      util::sleep_for(500);
-      continue;
-    } else if (err <= 0) {
-      break;
-    }
 
       AndroidLogEntry entry;
       err = android_log_processLogBuffer(&log_msg.entry_v1, &entry);
-    if (err < 0) {
+      if (err == 0) {
-      continue;
+        last_log_time.tv_sec = entry.tv_sec;
-    }
+        last_log_time.tv_nsec = entry.tv_nsec;
 
         MessageBuilder msg;
         auto androidEntry = msg.initEvent().initAndroidLog();
@@ -62,7 +48,10 @@ int main() {
 
         pm.send("androidLog", msg);
       }
+    }
 
-  android_logger_list_free(logger_list);
+    android_logger_list_free(loggers);
+    util::sleep_for(500);
+  }
   return 0;
 }