Fix race condition in dbengine (#7533)

3 files changed, 65 insertions, 32 deletions

diff --git a/daemon/main.c b/daemon/main.c
index ece8feb447..c8cd968fbf 100644
--- a/daemon/main.c
+++ b/daemon/main.c
@@ -340,10 +340,12 @@ int help(int exitcode) {
             "  -W unittest              Run internal unittests and exit.\n\n"
 #ifdef ENABLE_DBENGINE
             "  -W createdataset=N       Create a DB engine dataset of N seconds and exit.\n\n"
-            "  -W stresstest=A,B,C,D,E  Run a DB engine stress test for A seconds,\n"
+            "  -W stresstest=A,B,C,D,E,F\n"
+            "                           Run a DB engine stress test for A seconds,\n"
             "                           with B writers and C readers, with a ramp up\n"
             "                           time of D seconds for writers, a page cache\n"
-            "                           size of E MiB, and exit.\n\n"
+            "                           size of E MiB, an optional disk space limit\n"
+            "                           of F MiB and exit.\n\n"
 #endif
             "  -W set section option value\n"
             "                           set netdata.conf option from the command line.\n\n"
@@ -956,7 +958,7 @@ int main(int argc, char **argv) {
                         else if(strncmp(optarg, stresstest_string, strlen(stresstest_string)) == 0) {
                             char *endptr;
                             unsigned test_duration_sec = 0, dset_charts = 0, query_threads = 0, ramp_up_seconds = 0,
-                            page_cache_mb = 0;
+                            page_cache_mb = 0, disk_space_mb = 0;
 
                             optarg += strlen(stresstest_string);
                             test_duration_sec = (unsigned)strtoul(optarg, &endptr, 0);
@@ -968,8 +970,10 @@ int main(int argc, char **argv) {
                                 ramp_up_seconds = (unsigned)strtoul(endptr + 1, &endptr, 0);
                             if (',' == *endptr)
                                 page_cache_mb = (unsigned)strtoul(endptr + 1, &endptr, 0);
+                            if (',' == *endptr)
+                                disk_space_mb = (unsigned)strtoul(endptr + 1, &endptr, 0);
                             dbengine_stress_test(test_duration_sec, dset_charts, query_threads, ramp_up_seconds,
-                                                 page_cache_mb);
+                                                 page_cache_mb, disk_space_mb);
                             return 0;
                         }
 #endif
diff --git a/daemon/unit_test.c b/daemon/unit_test.c
index 2e59273214..bae2a3418e 100644
--- a/daemon/unit_test.c
+++ b/daemon/unit_test.c
@@ -1723,7 +1723,7 @@ int test_dbengine(void)
 
     default_rrd_memory_mode = RRD_MEMORY_MODE_DBENGINE;
 
-    debug(D_RRDHOST, "Initializing localhost with hostname 'unittest-dbengine'");
+    fprintf(stderr, "Initializing localhost with hostname 'unittest-dbengine'\n");
     host = dbengine_rrdhost_find_or_create("unittest-dbengine");
     if (NULL == host)
         return 1;
@@ -1915,6 +1915,9 @@ static void generate_dbengine_chart(void *arg)
         rrdset_done(st);
         thread_info->time_max = time_current;
     }
+    for (j = 0; j < DSET_DIMS; ++j) {
+        rrdeng_store_metric_finalize(rd[j]);
+    }
 }
 
 void generate_dbengine_dataset(unsigned history_seconds)
@@ -1935,7 +1938,7 @@ void generate_dbengine_dataset(unsigned history_seconds)
     default_rrdeng_disk_quota_mb -= default_rrdeng_disk_quota_mb * EXPECTED_COMPRESSION_RATIO / 100;
 
     error_log_limit_unlimited();
-    debug(D_RRDHOST, "Initializing localhost with hostname 'dbengine-dataset'");
+    fprintf(stderr, "Initializing localhost with hostname 'dbengine-dataset'\n");
 
     host = dbengine_rrdhost_find_or_create("dbengine-dataset");
     if (NULL == host)
@@ -1986,6 +1989,7 @@ struct dbengine_query_thread {
     unsigned history_seconds; /* how far back in the past to go */
     volatile long done; /* initialize to 0, set to 1 to stop thread */
     unsigned long errors, queries_nr, queried_metrics_nr; /* statistics */
+    uint8_t delete_old_data; /* if non zero then data are deleted when disk space is exhausted */
 
     struct dbengine_chart_thread *chart_threads[]; /* dset_charts elements */
 };
@@ -1995,7 +1999,7 @@ static void query_dbengine_chart(void *arg)
     struct dbengine_query_thread *thread_info = (struct dbengine_query_thread *)arg;
     const int DSET_CHARTS = thread_info->dset_charts;
     const int DSET_DIMS = thread_info->dset_dims;
-    time_t time_after, time_before, time_min, time_max, duration;
+    time_t time_after, time_before, time_min, time_approx_min, time_max, duration;
     int i, j, update_every = 1;
     RRDSET *st;
     RRDDIM *rd;
@@ -2015,6 +2019,13 @@ static void query_dbengine_chart(void *arg)
 
         time_min = thread_info->time_present - thread_info->history_seconds + 1;
         time_max = thread_info->chart_threads[i]->time_max;
+
+        if (thread_info->delete_old_data) {
+            /* A time window of twice the disk space is sufficient for compression space savings of up to 50% */
+            time_approx_min = time_max - (default_rrdeng_disk_quota_mb * 2 * 1024 * 1024) /
+                                         (((uint64_t) DSET_DIMS * DSET_CHARTS) * sizeof(storage_number));
+            time_min = MAX(time_min, time_approx_min);
+        }
         if (!time_max) {
             time_before = time_after = time_min;
         } else {
@@ -2030,18 +2041,22 @@ static void query_dbengine_chart(void *arg)
             expected = unpack_storage_number(pack_storage_number((calculated_number) generatedv, SN_EXISTS));
 
             if (unlikely(rd->state->query_ops.is_finished(&handle))) {
-                fprintf(stderr, "    DB-engine stresstest %s/%s: at %lu secs, expecting value "
-                                CALCULATED_NUMBER_FORMAT ", found data gap, ### E R R O R ###\n",
-                        st->name, rd->name, (unsigned long) time_now, expected);
-                ++thread_info->errors;
+                if (!thread_info->delete_old_data) { /* data validation only when we don't delete */
+                    fprintf(stderr, "    DB-engine stresstest %s/%s: at %lu secs, expecting value "
+                                    CALCULATED_NUMBER_FORMAT ", found data gap, ### E R R O R ###\n",
+                            st->name, rd->name, (unsigned long) time_now, expected);
+                    ++thread_info->errors;
+                }
                 break;
             }
             n = rd->state->query_ops.next_metric(&handle, &time_retrieved);
             if (SN_EMPTY_SLOT == n) {
-                fprintf(stderr, "    DB-engine stresstest %s/%s: at %lu secs, expecting value "
-                                CALCULATED_NUMBER_FORMAT ", found data gap, ### E R R O R ###\n",
-                        st->name, rd->name, (unsigned long) time_now, expected);
-                ++thread_info->errors;
+                if (!thread_info->delete_old_data) { /* data validation only when we don't delete */
+                    fprintf(stderr, "    DB-engine stresstest %s/%s: at %lu secs, expecting value "
+                                    CALCULATED_NUMBER_FORMAT ", found data gap, ### E R R O R ###\n",
+                            st->name, rd->name, (unsigned long) time_now, expected);
+                    ++thread_info->errors;
+                }
                 break;
             }
             ++thread_info->queried_metrics_nr;
@@ -2049,15 +2064,21 @@ static void query_dbengine_chart(void *arg)
 
             same = (calculated_number_round(value) == calculated_number_round(expected)) ? 1 : 0;
             if (!same) {
-                fprintf(stderr, "    DB-engine stresstest %s/%s: at %lu secs, expecting value "
-                                CALCULATED_NUMBER_FORMAT ", found " CALCULATED_NUMBER_FORMAT ", ### E R R O R ###\n",
-                        st->name, rd->name, (unsigned long) time_now, expected, value);
-                ++thread_info->errors;
+                if (!thread_info->delete_old_data) { /* data validation only when we don't delete */
+                    fprintf(stderr, "    DB-engine stresstest %s/%s: at %lu secs, expecting value "
+                                    CALCULATED_NUMBER_FORMAT ", found " CALCULATED_NUMBER_FORMAT
+                                    ", ### E R R O R ###\n",
+                            st->name, rd->name, (unsigned long) time_now, expected, value);
+                    ++thread_info->errors;
+                }
             }
             if (time_retrieved != time_now) {
-                fprintf(stderr, "    DB-engine stresstest %s/%s: at %lu secs, found timestamp %lu ### E R R O R ###\n",
-                        st->name, rd->name, (unsigned long) time_now, (unsigned long) time_retrieved);
-                ++thread_info->errors;
+                if (!thread_info->delete_old_data) { /* data validation only when we don't delete */
+                    fprintf(stderr,
+                            "    DB-engine stresstest %s/%s: at %lu secs, found timestamp %lu ### E R R O R ###\n",
+                            st->name, rd->name, (unsigned long) time_now, (unsigned long) time_retrieved);
+                    ++thread_info->errors;
+                }
             }
         }
         rd->state->query_ops.finalize(&handle);
@@ -2065,17 +2086,19 @@ static void query_dbengine_chart(void *arg)
 }
 
 void dbengine_stress_test(unsigned TEST_DURATION_SEC, unsigned DSET_CHARTS, unsigned QUERY_THREADS,
-                          unsigned RAMP_UP_SECONDS, unsigned PAGE_CACHE_MB)
+                          unsigned RAMP_UP_SECONDS, unsigned PAGE_CACHE_MB, unsigned DISK_SPACE_MB)
 {
     const unsigned DSET_DIMS = 128;
     const uint64_t EXPECTED_COMPRESSION_RATIO = 20;
-    const unsigned HISTORY_SECONDS = 3600 * 24 * 365; /* 1 year of history */
+    const unsigned HISTORY_SECONDS = 3600 * 24 * 365 * 50; /* 50 years of history */
     RRDHOST *host = NULL;
     struct dbengine_chart_thread **chart_threads;
     struct dbengine_query_thread **query_threads;
     unsigned i, j;
     time_t time_start, time_end;
 
+    error_log_limit_unlimited();
+
     if (!TEST_DURATION_SEC)
         TEST_DURATION_SEC = 10;
     if (!DSET_CHARTS)
@@ -2087,13 +2110,18 @@ void dbengine_stress_test(unsigned TEST_DURATION_SEC, unsigned DSET_CHARTS, unsi
 
     default_rrd_memory_mode = RRD_MEMORY_MODE_DBENGINE;
     default_rrdeng_page_cache_mb = PAGE_CACHE_MB;
-    // Worst case for uncompressible data
-    default_rrdeng_disk_quota_mb = (((uint64_t)DSET_DIMS * DSET_CHARTS) * sizeof(storage_number) * HISTORY_SECONDS) /
-                                   (1024 * 1024);
-    default_rrdeng_disk_quota_mb -= default_rrdeng_disk_quota_mb * EXPECTED_COMPRESSION_RATIO / 100;
+    if (DISK_SPACE_MB) {
+        fprintf(stderr, "By setting disk space limit data are allowed to be deleted. "
+                        "Data validation is turned off for this run.\n");
+        default_rrdeng_disk_quota_mb = DISK_SPACE_MB;
+    } else {
+        // Worst case for uncompressible data
+        default_rrdeng_disk_quota_mb =
+                (((uint64_t) DSET_DIMS * DSET_CHARTS) * sizeof(storage_number) * HISTORY_SECONDS) / (1024 * 1024);
+        default_rrdeng_disk_quota_mb -= default_rrdeng_disk_quota_mb * EXPECTED_COMPRESSION_RATIO / 100;
+    }
 
-    error_log_limit_unlimited();
-    debug(D_RRDHOST, "Initializing localhost with hostname 'dbengine-stress-test'");
+    fprintf(stderr, "Initializing localhost with hostname 'dbengine-stress-test'\n");
 
     host = dbengine_rrdhost_find_or_create("dbengine-stress-test");
     if (NULL == host)
@@ -2112,7 +2140,7 @@ void dbengine_stress_test(unsigned TEST_DURATION_SEC, unsigned DSET_CHARTS, unsi
                     "%u MiB of page cache.\n",
                     RAMP_UP_SECONDS, TEST_DURATION_SEC, DSET_CHARTS, QUERY_THREADS, PAGE_CACHE_MB);
 
-    time_start = now_realtime_sec();
+    time_start = now_realtime_sec() + HISTORY_SECONDS; /* move history to the future */
     for (i = 0 ; i < DSET_CHARTS ; ++i) {
         chart_threads[i]->host = host;
         chart_threads[i]->chartname = "random";
@@ -2146,6 +2174,7 @@ void dbengine_stress_test(unsigned TEST_DURATION_SEC, unsigned DSET_CHARTS, unsi
         for (j = 0 ; j < DSET_CHARTS ; ++j) {
             query_threads[i]->chart_threads[j] = chart_threads[j];
         }
+        query_threads[i]->delete_old_data = DISK_SPACE_MB ? 1 : 0;
         assert(0 == uv_thread_create(&query_threads[i]->thread, query_dbengine_chart, query_threads[i]));
     }
     sleep(TEST_DURATION_SEC);
diff --git a/daemon/unit_test.h b/daemon/unit_test.h
index 230a700858..79d415be04 100644
--- a/daemon/unit_test.h
+++ b/daemon/unit_test.h
@@ -12,7 +12,7 @@ extern int unit_test_buffer(void);
 extern int test_dbengine(void);
 extern void generate_dbengine_dataset(unsigned history_seconds);
 extern void dbengine_stress_test(unsigned TEST_DURATION_SEC, unsigned DSET_CHARTS, unsigned QUERY_THREADS,
-                                 unsigned RAMP_UP_SECONDS, unsigned PAGE_CACHE_MB);
+                                 unsigned RAMP_UP_SECONDS, unsigned PAGE_CACHE_MB, unsigned DISK_SPACE_MB);
 
 #endif