Add 'watch' command to CameraService

Currently there is no way to monitor tags and dump per frame data from
Camera devices without calling dumpsys, which in turn dumps a lot of
unnecessary information.

This CL adds a 'watch' command to CameraService which can be called
through `cmd`. 'watch' provides a path to manage tag monitoring without
dumpsys. 'watch' currently has four functions:
1. start <taglist>: starts mornitoring the provided tags in attached
                    devices.
2. stop: stop monitoring all tags
3. live: prints monitored information to the terminal live
4. dump: dumps any collected camera traces

This CL adds a function to camera device each for the three tag
monitoring function listed above.

Test: n/a
Bug: 199746421
Change-Id: Ia5ce13f6e50c82085afcc676309cdbffef915a41
diff --git a/services/camera/libcameraservice/utils/CameraTraces.cpp b/services/camera/libcameraservice/utils/CameraTraces.cpp
index 0198690..0cd4f5d 100644
--- a/services/camera/libcameraservice/utils/CameraTraces.cpp
+++ b/services/camera/libcameraservice/utils/CameraTraces.cpp
@@ -64,7 +64,7 @@
     ATRACE_END();
 }
 
-status_t CameraTraces::dump(int fd, const Vector<String16> &args __attribute__((unused))) {
+status_t CameraTraces::dump(int fd) {
     ALOGV("%s: fd = %d", __FUNCTION__, fd);
     Mutex::Autolock al(sImpl.tracesLock);
     List<ProcessCallStack>& pcsList = sImpl.pcsList;
diff --git a/services/camera/libcameraservice/utils/CameraTraces.h b/services/camera/libcameraservice/utils/CameraTraces.h
index 13ca16d..71fa334 100644
--- a/services/camera/libcameraservice/utils/CameraTraces.h
+++ b/services/camera/libcameraservice/utils/CameraTraces.h
@@ -42,7 +42,7 @@
      *
      * <p>Each line is indented by DUMP_INDENT spaces.</p>
      */
-    static status_t dump(int fd, const Vector<String16>& args);
+    static status_t dump(int fd);
 
 private:
     enum {
diff --git a/services/camera/libcameraservice/utils/TagMonitor.cpp b/services/camera/libcameraservice/utils/TagMonitor.cpp
index 4488098..461f5e9 100644
--- a/services/camera/libcameraservice/utils/TagMonitor.cpp
+++ b/services/camera/libcameraservice/utils/TagMonitor.cpp
@@ -239,38 +239,59 @@
     } else {
         dprintf(fd, "     Tag monitoring disabled (enable with -m <name1,..,nameN>)\n");
     }
-    if (mMonitoringEvents.size() > 0) {
-        dprintf(fd, "     Monitored tag event log:\n");
-        for (const auto& event : mMonitoringEvents) {
-            int indentation = (event.source == REQUEST) ? 15 : 30;
-            dprintf(fd, "        f%d:%" PRId64 "ns:%*s%*s%s.%s: ",
-                    event.frameNumber, event.timestamp,
-                    2, event.cameraId.c_str(),
-                    indentation,
-                    event.source == REQUEST ? "REQ:" : "RES:",
-                    get_local_camera_metadata_section_name_vendor_id(event.tag,
-                            mVendorTagId),
-                    get_local_camera_metadata_tag_name_vendor_id(event.tag,
-                            mVendorTagId));
-            if (event.newData.size() == 0) {
-                dprintf(fd, " (Removed)\n");
-            } else {
-                printData(fd, event.newData.data(), event.tag,
-                        event.type, event.newData.size() / camera_metadata_type_size[event.type],
-                        indentation + 18, event.outputStreamIds, event.inputStreamId);
-            }
-        }
-    }
 
+    if (mMonitoringEvents.size() == 0) { return; }
+
+    dprintf(fd, "     Monitored tag event log:\n");
+
+    std::vector<std::string> eventStrs;
+    dumpMonitoredTagEventsToVectorLocked(eventStrs);
+    for (const std::string &eventStr : eventStrs) {
+        dprintf(fd, "        %s", eventStr.c_str());
+    }
 }
 
-// TODO: Consolidate with printData from camera_metadata.h
+void TagMonitor::getLatestMonitoredTagEvents(std::vector<std::string> &out) {
+    std::lock_guard<std::mutex> lock(mMonitorMutex);
+    dumpMonitoredTagEventsToVectorLocked(out);
+}
+
+void TagMonitor::dumpMonitoredTagEventsToVectorLocked(std::vector<std::string> &vec) {
+    if (mMonitoringEvents.size() == 0) { return; }
+
+    for (const auto& event : mMonitoringEvents) {
+        int indentation = (event.source == REQUEST) ? 15 : 30;
+        String8 eventString = String8::format("f%d:%" PRId64 "ns:%*s%*s%s.%s: ",
+                event.frameNumber, event.timestamp,
+                2, event.cameraId.c_str(),
+                indentation,
+                event.source == REQUEST ? "REQ:" : "RES:",
+                get_local_camera_metadata_section_name_vendor_id(event.tag, mVendorTagId),
+                get_local_camera_metadata_tag_name_vendor_id(event.tag, mVendorTagId));
+        if (event.newData.size() == 0) {
+            eventString += " (Removed)";
+        } else {
+            eventString += getEventDataString(event.newData.data(),
+                                    event.tag,
+                                    event.type,
+                                    event.newData.size() / camera_metadata_type_size[event.type],
+                                    indentation + 18,
+                                    event.outputStreamIds,
+                                    event.inputStreamId);
+        }
+        vec.emplace_back(eventString.string());
+    }
+}
 
 #define CAMERA_METADATA_ENUM_STRING_MAX_SIZE 29
 
-void TagMonitor::printData(int fd, const uint8_t *data_ptr, uint32_t tag,
-        int type, int count, int indentation, const std::unordered_set<int32_t> &outputStreamIds,
-        int32_t inputStreamId) {
+String8 TagMonitor::getEventDataString(const uint8_t* data_ptr,
+                                    uint32_t tag,
+                                    int type,
+                                    int count,
+                                    int indentation,
+                                    const std::unordered_set<int32_t>& outputStreamIds,
+                                    int32_t inputStreamId) {
     static int values_per_line[NUM_TYPES] = {
         [TYPE_BYTE]     = 16,
         [TYPE_INT32]    = 8,
@@ -279,6 +300,7 @@
         [TYPE_DOUBLE]   = 4,
         [TYPE_RATIONAL] = 4,
     };
+
     size_t type_size = camera_metadata_type_size[type];
     char value_string_tmp[CAMERA_METADATA_ENUM_STRING_MAX_SIZE];
     uint32_t value;
@@ -286,10 +308,11 @@
     int lines = count / values_per_line[type];
     if (count % values_per_line[type] != 0) lines++;
 
+    String8 returnStr = String8();
     int index = 0;
     int j, k;
     for (j = 0; j < lines; j++) {
-        dprintf(fd, "%*s[", (j != 0) ? indentation + 4 : 0, "");
+        returnStr.appendFormat("%*s[", (j != 0) ? indentation + 4 : 0, "");
         for (k = 0;
              k < values_per_line[type] && count > 0;
              k++, count--, index += type_size) {
@@ -302,10 +325,9 @@
                                                      value_string_tmp,
                                                      sizeof(value_string_tmp))
                         == OK) {
-                        dprintf(fd, "%s ", value_string_tmp);
+                        returnStr += value_string_tmp;
                     } else {
-                        dprintf(fd, "%hhu ",
-                                *(data_ptr + index));
+                        returnStr.appendFormat("%hhu", *(data_ptr + index));
                     }
                     break;
                 case TYPE_INT32:
@@ -316,47 +338,43 @@
                                                      value_string_tmp,
                                                      sizeof(value_string_tmp))
                         == OK) {
-                        dprintf(fd, "%s ", value_string_tmp);
+                        returnStr += value_string_tmp;
                     } else {
-                        dprintf(fd, "%" PRId32 " ",
-                                *(int32_t*)(data_ptr + index));
+                        returnStr.appendFormat("%" PRId32 " ", *(int32_t*)(data_ptr + index));
                     }
                     break;
                 case TYPE_FLOAT:
-                    dprintf(fd, "%0.8f ",
-                            *(float*)(data_ptr + index));
+                    returnStr.appendFormat("%0.8f", *(float*)(data_ptr + index));
                     break;
                 case TYPE_INT64:
-                    dprintf(fd, "%" PRId64 " ",
-                            *(int64_t*)(data_ptr + index));
+                    returnStr.appendFormat("%" PRId64 " ", *(int64_t*)(data_ptr + index));
                     break;
                 case TYPE_DOUBLE:
-                    dprintf(fd, "%0.8f ",
-                            *(double*)(data_ptr + index));
+                    returnStr.appendFormat("%0.8f ", *(double*)(data_ptr + index));
                     break;
                 case TYPE_RATIONAL: {
                     int32_t numerator = *(int32_t*)(data_ptr + index);
                     int32_t denominator = *(int32_t*)(data_ptr + index + 4);
-                    dprintf(fd, "(%d / %d) ",
-                            numerator, denominator);
+                    returnStr.appendFormat("(%d / %d) ", numerator, denominator);
                     break;
                 }
                 default:
-                    dprintf(fd, "??? ");
+                    returnStr += "??? ";
             }
         }
-        dprintf(fd, "] ");
-        if (outputStreamIds.size() > 0) {
-            dprintf(fd, "output stream ids: ");
+        returnStr += "] ";
+        if (!outputStreamIds.empty()) {
+            returnStr += "output stream ids: ";
             for (const auto &id : outputStreamIds) {
-                dprintf(fd, " %d ", id);
+                returnStr.appendFormat(" %d ", id);
             }
         }
         if (inputStreamId != -1) {
-            dprintf(fd, "input stream id: %d", inputStreamId);
+            returnStr.appendFormat("input stream id: %d", inputStreamId);
         }
-        dprintf(fd, "\n");
+        returnStr += "\n";
     }
+    return returnStr;
 }
 
 template<typename T>
diff --git a/services/camera/libcameraservice/utils/TagMonitor.h b/services/camera/libcameraservice/utils/TagMonitor.h
index f6df4b7..088d6fe 100644
--- a/services/camera/libcameraservice/utils/TagMonitor.h
+++ b/services/camera/libcameraservice/utils/TagMonitor.h
@@ -74,11 +74,23 @@
     // Dump current event log to the provided fd
     void dumpMonitoredMetadata(int fd);
 
-  private:
+    // Dumps the latest monitored Tag events to the passed vector.
+    // NOTE: The events are appended to the vector in reverser chronological order
+    // (i.e. most recent first)
+    void getLatestMonitoredTagEvents(std::vector<std::string> &out);
 
-    static void printData(int fd, const uint8_t *data_ptr, uint32_t tag,
-            int type, int count, int indentation,
-            const std::unordered_set<int32_t> &outputStreamIds, int32_t inputStreamId);
+  private:
+    // Dumps monitored tag events to the passed vector without acquiring
+    // mMonitorMutex. mMonitorMutex must be acquired before calling this
+    // function.
+    void dumpMonitoredTagEventsToVectorLocked(std::vector<std::string> &out);
+
+    static String8 getEventDataString(const uint8_t *data_ptr,
+                                       uint32_t tag, int type,
+                                       int count,
+                                       int indentation,
+                                       const std::unordered_set<int32_t> &outputStreamIds,
+                                       int32_t inputStreamId);
 
     void monitorSingleMetadata(TagMonitor::eventSource source, int64_t frameNumber,
             nsecs_t timestamp, const std::string& cameraId, uint32_t tag,