lmkd: Isolate statslog related code from lmkd code

Move statsd related code out of lmkd.c to minimize ifdefs sprinkled around
the code and make it more maintainable.

Bug: 74119935
Test: lmkd_unit_test
Change-Id: Ib22f90fd380b9a31e09ab18ef16787bc07415ddf
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
diff --git a/lmkd/statslog.c b/lmkd/statslog.c
index f3a6e55..c0fd6df 100644
--- a/lmkd/statslog.c
+++ b/lmkd/statslog.c
@@ -18,11 +18,21 @@
 #include <errno.h>
 #include <log/log_id.h>
 #include <stats_event_list.h>
+#include <statslog.h>
+#include <stdlib.h>
+#include <string.h>
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
 
+#ifdef LMKD_LOG_STATS
+
 #define LINE_MAX 128
+#define STRINGIFY(x) STRINGIFY_INTERNAL(x)
+#define STRINGIFY_INTERNAL(x) #x
+
+static bool enable_stats_log;
+static android_log_context log_ctx;
 
 struct proc {
     int pid;
@@ -41,34 +51,53 @@
     return (int64_t)t.tv_sec * 1000000000LL + t.tv_nsec;
 }
 
+void statslog_init() {
+    enable_stats_log = property_get_bool("ro.lmk.log_stats", false);
+
+    if (enable_stats_log) {
+        log_ctx = create_android_logger(kStatsEventTag);
+    }
+}
+
+void statslog_destroy() {
+    if (log_ctx) {
+        android_log_destroy(&log_ctx);
+    }
+}
+
 /**
  * Logs the change in LMKD state which is used as start/stop boundaries for logging
  * LMK_KILL_OCCURRED event.
  * Code: LMK_STATE_CHANGED = 54
  */
 int
-stats_write_lmk_state_changed(android_log_context ctx, int32_t code, int32_t state) {
-    assert(ctx != NULL);
+stats_write_lmk_state_changed(int32_t code, int32_t state) {
     int ret = -EINVAL;
-    if (!ctx) {
+
+    if (!enable_stats_log) {
         return ret;
     }
 
-    reset_log_context(ctx);
-
-    if ((ret = android_log_write_int64(ctx, getElapsedRealTimeNs())) < 0) {
+    assert(log_ctx != NULL);
+    if (!log_ctx) {
         return ret;
     }
 
-    if ((ret = android_log_write_int32(ctx, code)) < 0) {
+    reset_log_context(log_ctx);
+
+    if ((ret = android_log_write_int64(log_ctx, getElapsedRealTimeNs())) < 0) {
         return ret;
     }
 
-    if ((ret = android_log_write_int32(ctx, state)) < 0) {
+    if ((ret = android_log_write_int32(log_ctx, code)) < 0) {
         return ret;
     }
 
-    return write_to_logger(ctx, LOG_ID_STATS);
+    if ((ret = android_log_write_int32(log_ctx, state)) < 0) {
+        return ret;
+    }
+
+    return write_to_logger(log_ctx, LOG_ID_STATS);
 }
 
 static struct proc* pid_lookup(int pid) {
@@ -87,92 +116,261 @@
  * Code: LMK_KILL_OCCURRED = 51
  */
 int
-stats_write_lmk_kill_occurred(android_log_context ctx, int32_t code, int32_t uid,
-                              char const* process_name, int32_t oom_score, int64_t pgfault,
-                              int64_t pgmajfault, int64_t rss_in_bytes, int64_t cache_in_bytes,
-                              int64_t swap_in_bytes, int64_t process_start_time_ns,
-                              int32_t min_oom_score) {
-    assert(ctx != NULL);
+stats_write_lmk_kill_occurred(int32_t code, int32_t uid, char const* process_name,
+                              int32_t oom_score, int32_t min_oom_score, int tasksize,
+                              struct memory_stat *mem_st) {
     int ret = -EINVAL;
-    if (!ctx) {
+    if (!enable_stats_log) {
         return ret;
     }
-    reset_log_context(ctx);
+    if (!log_ctx) {
+        return ret;
+    }
+    reset_log_context(log_ctx);
 
-    if ((ret = android_log_write_int64(ctx, getElapsedRealTimeNs())) < 0) {
+    if ((ret = android_log_write_int64(log_ctx, getElapsedRealTimeNs())) < 0) {
         return ret;
     }
 
-    if ((ret = android_log_write_int32(ctx, code)) < 0) {
+    if ((ret = android_log_write_int32(log_ctx, code)) < 0) {
         return ret;
     }
 
-    if ((ret = android_log_write_int32(ctx, uid)) < 0) {
+    if ((ret = android_log_write_int32(log_ctx, uid)) < 0) {
         return ret;
     }
 
-    if ((ret = android_log_write_string8(ctx, (process_name == NULL) ? "" : process_name)) < 0) {
+    if ((ret = android_log_write_string8(log_ctx, (process_name == NULL) ? "" : process_name)) < 0) {
         return ret;
     }
 
-    if ((ret = android_log_write_int32(ctx, oom_score)) < 0) {
+    if ((ret = android_log_write_int32(log_ctx, oom_score)) < 0) {
         return ret;
     }
 
-    if ((ret = android_log_write_int64(ctx, pgfault)) < 0) {
+    if ((ret = android_log_write_int64(log_ctx, mem_st ? mem_st->pgfault : -1)) < 0) {
         return ret;
     }
 
-    if ((ret = android_log_write_int64(ctx, pgmajfault)) < 0) {
+    if ((ret = android_log_write_int64(log_ctx, mem_st ? mem_st->pgmajfault : -1)) < 0) {
         return ret;
     }
 
-    if ((ret = android_log_write_int64(ctx, rss_in_bytes)) < 0) {
+    if ((ret = android_log_write_int64(log_ctx, mem_st ? mem_st->rss_in_bytes
+                                                       : tasksize * BYTES_IN_KILOBYTE)) < 0) {
         return ret;
     }
 
-    if ((ret = android_log_write_int64(ctx, cache_in_bytes)) < 0) {
+    if ((ret = android_log_write_int64(log_ctx, mem_st ? mem_st->cache_in_bytes : -1)) < 0) {
         return ret;
     }
 
-    if ((ret = android_log_write_int64(ctx, swap_in_bytes)) < 0) {
+    if ((ret = android_log_write_int64(log_ctx, mem_st ? mem_st->swap_in_bytes : -1)) < 0) {
         return ret;
     }
 
-    if ((ret = android_log_write_int64(ctx, process_start_time_ns)) < 0) {
+    if ((ret = android_log_write_int64(log_ctx, mem_st ? mem_st->process_start_time_ns
+                                                       : -1)) < 0) {
         return ret;
     }
 
-    if ((ret = android_log_write_int32(ctx, min_oom_score)) < 0) {
+    if ((ret = android_log_write_int32(log_ctx, min_oom_score)) < 0) {
         return ret;
     }
 
-    return write_to_logger(ctx, LOG_ID_STATS);
+    return write_to_logger(log_ctx, LOG_ID_STATS);
 }
 
-int stats_write_lmk_kill_occurred_pid(android_log_context ctx, int32_t code, int32_t uid, int pid,
-                                      int32_t oom_score, int64_t pgfault, int64_t pgmajfault,
-                                      int64_t rss_in_bytes, int64_t cache_in_bytes,
-                                      int64_t swap_in_bytes, int64_t process_start_time_ns,
-                                      int32_t min_oom_score) {
+static int stats_write_lmk_kill_occurred_pid(int32_t code, int32_t uid, int pid,
+                                      int32_t oom_score, int32_t min_oom_score, int tasksize,
+                                      struct memory_stat *mem_st) {
     struct proc* proc = pid_lookup(pid);
     if (!proc) return -EINVAL;
 
-    return stats_write_lmk_kill_occurred(ctx, code, uid, proc->taskname, oom_score, pgfault,
-                                         pgmajfault, rss_in_bytes, cache_in_bytes, swap_in_bytes,
-                                         process_start_time_ns, min_oom_score);
+    return stats_write_lmk_kill_occurred(code, uid, proc->taskname, oom_score, min_oom_score,
+                                         tasksize, mem_st);
+}
+
+static void memory_stat_parse_line(char* line, struct memory_stat* mem_st) {
+    char key[LINE_MAX + 1];
+    int64_t value;
+
+    sscanf(line, "%" STRINGIFY(LINE_MAX) "s  %" SCNd64 "", key, &value);
+
+    if (strcmp(key, "total_") < 0) {
+        return;
+    }
+
+    if (!strcmp(key, "total_pgfault"))
+        mem_st->pgfault = value;
+    else if (!strcmp(key, "total_pgmajfault"))
+        mem_st->pgmajfault = value;
+    else if (!strcmp(key, "total_rss"))
+        mem_st->rss_in_bytes = value;
+    else if (!strcmp(key, "total_cache"))
+        mem_st->cache_in_bytes = value;
+    else if (!strcmp(key, "total_swap"))
+        mem_st->swap_in_bytes = value;
+}
+
+static int memory_stat_from_cgroup(struct memory_stat* mem_st, int pid, uid_t uid) {
+    FILE *fp;
+    char buf[PATH_MAX];
+
+    snprintf(buf, sizeof(buf), MEMCG_PROCESS_MEMORY_STAT_PATH, uid, pid);
+
+    fp = fopen(buf, "r");
+
+    if (fp == NULL) {
+        return -1;
+    }
+
+    while (fgets(buf, PAGE_SIZE, fp) != NULL) {
+        memory_stat_parse_line(buf, mem_st);
+    }
+    fclose(fp);
+
+    return 0;
+}
+
+static int memory_stat_from_procfs(struct memory_stat* mem_st, int pid) {
+    char path[PATH_MAX];
+    char buffer[PROC_STAT_BUFFER_SIZE];
+    int fd, ret;
+
+    snprintf(path, sizeof(path), PROC_STAT_FILE_PATH, pid);
+    if ((fd = open(path, O_RDONLY | O_CLOEXEC)) < 0) {
+        return -1;
+    }
+
+    ret = read(fd, buffer, sizeof(buffer));
+    if (ret < 0) {
+        close(fd);
+        return -1;
+    }
+    close(fd);
+
+    // field 10 is pgfault
+    // field 12 is pgmajfault
+    // field 22 is starttime
+    // field 24 is rss_in_pages
+    int64_t pgfault = 0, pgmajfault = 0, starttime = 0, rss_in_pages = 0;
+    if (sscanf(buffer,
+               "%*u %*s %*s %*d %*d %*d %*d %*d %*d %" SCNd64 " %*d "
+               "%" SCNd64 " %*d %*u %*u %*d %*d %*d %*d %*d %*d "
+               "%" SCNd64 " %*d %" SCNd64 "",
+               &pgfault, &pgmajfault, &starttime, &rss_in_pages) != 4) {
+        return -1;
+    }
+    mem_st->pgfault = pgfault;
+    mem_st->pgmajfault = pgmajfault;
+    mem_st->rss_in_bytes = (rss_in_pages * PAGE_SIZE);
+    mem_st->process_start_time_ns = starttime * (NS_PER_SEC / sysconf(_SC_CLK_TCK));
+
+    return 0;
+}
+
+struct memory_stat *stats_read_memory_stat(bool per_app_memcg, int pid, uid_t uid) {
+    static struct memory_stat mem_st = {};
+
+    if (!enable_stats_log) {
+        return NULL;
+    }
+
+    if (per_app_memcg) {
+        if (memory_stat_from_cgroup(&mem_st, pid, uid) == 0) {
+            return &mem_st;
+        }
+    } else {
+        if (memory_stat_from_procfs(&mem_st, pid) == 0) {
+            return &mem_st;
+        }
+    }
+
+    return NULL;
+}
+
+static void poll_kernel(int poll_fd) {
+    if (poll_fd == -1) {
+        // not waiting
+        return;
+    }
+
+    while (1) {
+        char rd_buf[256];
+        int bytes_read =
+                TEMP_FAILURE_RETRY(pread(poll_fd, (void*)rd_buf, sizeof(rd_buf), 0));
+        if (bytes_read <= 0) break;
+        rd_buf[bytes_read] = '\0';
+
+        int64_t pid;
+        int64_t uid;
+        int64_t group_leader_pid;
+        int64_t rss_in_pages;
+        struct memory_stat mem_st = {};
+        int16_t oom_score_adj;
+        int16_t min_score_adj;
+        int64_t starttime;
+        char* taskname = 0;
+
+        int fields_read = sscanf(rd_buf,
+                                 "%" SCNd64 " %" SCNd64 " %" SCNd64 " %" SCNd64 " %" SCNd64
+                                 " %" SCNd64 " %" SCNd16 " %" SCNd16 " %" SCNd64 "\n%m[^\n]",
+                                 &pid, &uid, &group_leader_pid, &mem_st.pgfault,
+                                 &mem_st.pgmajfault, &rss_in_pages, &oom_score_adj,
+                                 &min_score_adj, &starttime, &taskname);
+
+        /* only the death of the group leader process is logged */
+        if (fields_read == 10 && group_leader_pid == pid) {
+            mem_st.process_start_time_ns = starttime * (NS_PER_SEC / sysconf(_SC_CLK_TCK));
+            mem_st.rss_in_bytes = rss_in_pages * PAGE_SIZE;
+            stats_write_lmk_kill_occurred_pid(LMK_KILL_OCCURRED, uid, pid, oom_score_adj,
+                                              min_score_adj, 0, &mem_st);
+        }
+
+        free(taskname);
+    }
+}
+
+bool init_poll_kernel(struct kernel_poll_info *poll_info) {
+    if (!enable_stats_log) {
+        return false;
+    }
+
+    poll_info->poll_fd =
+            TEMP_FAILURE_RETRY(open("/proc/lowmemorykiller", O_RDONLY | O_NONBLOCK | O_CLOEXEC));
+
+    if (poll_info->poll_fd < 0) {
+        ALOGE("kernel lmk event file could not be opened; errno=%d", errno);
+        return false;
+    }
+    poll_info->handler = poll_kernel;
+
+    return true;
 }
 
 static void proc_insert(struct proc* procp) {
-    if (!pidhash)
+    if (!pidhash) {
         pidhash = calloc(PIDHASH_SZ, sizeof(struct proc));
+    }
+
     int hval = pid_hashfn(procp->pid);
     procp->pidhash_next = pidhash[hval];
     pidhash[hval] = procp;
 }
 
-void stats_remove_taskname(int pid) {
-    if (!pidhash) return;
+void stats_remove_taskname(int pid, int poll_fd) {
+    if (!enable_stats_log || !pidhash) {
+        return;
+    }
+
+    /*
+     * Perform an extra check before the pid is removed, after which it
+     * will be impossible for poll_kernel to get the taskname. poll_kernel()
+     * is potentially a long-running blocking function; however this method
+     * handles AMS requests but does not block AMS.
+     */
+    poll_kernel(poll_fd);
 
     int hval = pid_hashfn(pid);
     struct proc* procp;
@@ -193,12 +391,19 @@
     free(procp);
 }
 
-void stats_store_taskname(int pid, const char* taskname) {
-    struct proc* procp = pid_lookup(pid);
-    if (procp != NULL && strcmp(procp->taskname, taskname) == 0)
+void stats_store_taskname(int pid, const char* taskname, int poll_fd) {
+    if (!enable_stats_log) {
         return;
+    }
+
+    struct proc* procp = pid_lookup(pid);
+    if (procp != NULL) {
+        if (strcmp(procp->taskname, taskname) == 0) {
+            return;
+        }
+        stats_remove_taskname(pid, poll_fd);
+    }
     procp = malloc(sizeof(struct proc));
-    stats_remove_taskname(pid);
     procp->pid = pid;
     strncpy(procp->taskname, taskname, LINE_MAX - 1);
     procp->taskname[LINE_MAX - 1] = '\0';
@@ -206,7 +411,10 @@
 }
 
 void stats_purge_tasknames() {
-    if (!pidhash) return;
+    if (!enable_stats_log || !pidhash) {
+        return;
+    }
+
     struct proc* procp;
     struct proc* next;
     int i;
@@ -220,3 +428,5 @@
     }
     memset(pidhash, 0, PIDHASH_SZ * sizeof(struct proc));
 }
+
+#endif /* LMKD_LOG_STATS */