Merge "logd: don't poll() before recvmsg()" am: bf3b47a031

Change-Id: I35b3a5e581163838d3154100c38719547a4fa7b2

logd/LogListener.cpp

@@ -22,6 +22,8 @@
 #include <sys/un.h>
 #include <unistd.h>
 
+#include <thread>
+
 #include <cutils/sockets.h>
 #include <private/android_filesystem_config.h>
 #include <private/android_logger.h>
@@ -31,33 +33,47 @@
 #include "LogUtils.h"
 
 LogListener::LogListener(LogBuffer* buf, LogReader* reader)
-    : SocketListener(getLogSocket(), false), logbuf(buf), reader(reader) {}
+    : socket_(GetLogSocket()), logbuf_(buf), reader_(reader) {}
 
-bool LogListener::onDataAvailable(SocketClient* cli) {
+bool LogListener::StartListener() {
+    if (socket_ <= 0) {
+        return false;
+    }
+    auto thread = std::thread(&LogListener::ThreadFunction, this);
+    thread.detach();
+    return true;
+}
+
+void LogListener::ThreadFunction() {
     static bool name_set;
     if (!name_set) {
         prctl(PR_SET_NAME, "logd.writer");
         name_set = true;
     }
 
+    while (true) {
+        HandleData();
+    }
+}
+
+void LogListener::HandleData() {
     // + 1 to ensure null terminator if MAX_PAYLOAD buffer is received
-    char buffer[sizeof(android_log_header_t) + LOGGER_ENTRY_MAX_PAYLOAD + 1];
-    struct iovec iov = { buffer, sizeof(buffer) - 1 };
+    __attribute__((uninitialized)) char
+            buffer[sizeof(android_log_header_t) + LOGGER_ENTRY_MAX_PAYLOAD + 1];
+    struct iovec iov = {buffer, sizeof(buffer) - 1};
 
     alignas(4) char control[CMSG_SPACE(sizeof(struct ucred))];
     struct msghdr hdr = {
         nullptr, 0, &iov, 1, control, sizeof(control), 0,
     };
 
-    int socket = cli->getSocket();
-
     // To clear the entire buffer is secure/safe, but this contributes to 1.68%
     // overhead under logging load. We are safe because we check counts, but
     // still need to clear null terminator
     // memset(buffer, 0, sizeof(buffer));
-    ssize_t n = recvmsg(socket, &hdr, 0);
+    ssize_t n = recvmsg(socket_, &hdr, 0);
     if (n <= (ssize_t)(sizeof(android_log_header_t))) {
-        return false;
+        return;
     }
 
     buffer[n] = 0;
@@ -75,14 +91,14 @@ bool LogListener::onDataAvailable(SocketClient* cli) {
     }
 
     if (cred == nullptr) {
-        return false;
+        return;
     }
 
     if (cred->uid == AID_LOGD) {
         // ignore log messages we send to ourself.
         // Such log messages are often generated by libraries we depend on
         // which use standard Android logging.
-        return false;
+        return;
     }
 
     android_log_header_t* header =
@@ -90,13 +106,13 @@ bool LogListener::onDataAvailable(SocketClient* cli) {
     log_id_t logId = static_cast<log_id_t>(header->id);
     if (/* logId < LOG_ID_MIN || */ logId >= LOG_ID_MAX ||
         logId == LOG_ID_KERNEL) {
-        return false;
+        return;
     }
 
     if ((logId == LOG_ID_SECURITY) &&
         (!__android_log_security() ||
          !clientHasLogCredentials(cred->uid, cred->gid, cred->pid))) {
-        return false;
+        return;
     }
 
     char* msg = ((char*)buffer) + sizeof(android_log_header_t);
@@ -105,16 +121,16 @@ bool LogListener::onDataAvailable(SocketClient* cli) {
     // NB: hdr.msg_flags & MSG_TRUNC is not tested, silently passing a
     // truncated message to the logs.
 
-    int res = logbuf->log(logId, header->realtime, cred->uid, cred->pid, header->tid, msg,
-                          ((size_t)n <= UINT16_MAX) ? (uint16_t)n : UINT16_MAX);
+    int res = logbuf_->log(logId, header->realtime, cred->uid, cred->pid, header->tid, msg,
+                           ((size_t)n <= UINT16_MAX) ? (uint16_t)n : UINT16_MAX);
     if (res > 0) {
-        reader->notifyNewLog(static_cast<unsigned int>(1 << logId));
+        reader_->notifyNewLog(static_cast<unsigned int>(1 << logId));
     }
 
-    return true;
+    return;
 }
 
-int LogListener::getLogSocket() {
+int LogListener::GetLogSocket() {
     static const char socketName[] = "logdw";
     int sock = android_get_control_socket(socketName);
 

logd/LogListener.h

@@ -14,24 +14,22 @@
  * limitations under the License.
  */
 
-#ifndef _LOGD_LOG_LISTENER_H__
-#define _LOGD_LOG_LISTENER_H__
+#pragma once
 
-#include <sysutils/SocketListener.h>
+#include "LogBuffer.h"
 #include "LogReader.h"
 
-class LogListener : public SocketListener {
-    LogBuffer* logbuf;
-    LogReader* reader;
+class LogListener {
+  public:
+    LogListener(LogBuffer* buf, LogReader* reader);
+    bool StartListener();
 
-   public:
-     LogListener(LogBuffer* buf, LogReader* reader);
+  private:
+    void ThreadFunction();
+    void HandleData();
+    static int GetLogSocket();
 
-   protected:
-    virtual bool onDataAvailable(SocketClient* cli);
-
-   private:
-    static int getLogSocket();
+    int socket_;
+    LogBuffer* logbuf_;
+    LogReader* reader_;
 };
-
-#endif

logd/main.cpp

@@ -304,8 +304,7 @@ int main(int argc, char* argv[]) {
     // and LogReader is notified to send updates to connected clients.
 
     LogListener* swl = new LogListener(logBuf, reader);
-    // Backlog and /proc/sys/net/unix/max_dgram_qlen set to large value
-    if (swl->startListener(600)) {
+    if (!swl->StartListener()) {
         return EXIT_FAILURE;
     }