1 files changed, 86 insertions, 0 deletions
diff --git a/database/engine/metadata_log/compaction.c b/database/engine/metadata_log/compaction.c
new file mode 100644
index 000000000..ba19e1edf
--- /dev/null
+++ b/database/engine/metadata_log/compaction.c
@@ -0,0 +1,86 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+#define NETDATA_RRD_INTERNALS
+
+#include "metadatalog.h"
+
+/* Return 0 on success. */
+int compaction_failure_recovery(struct metalog_instance *ctx, struct metadata_logfile **metalogfiles,
+                                 unsigned *matched_files)
+{
+    int ret;
+    unsigned starting_fileno, fileno, i, j, recovered_files;
+    struct metadata_logfile *metalogfile = NULL, *compactionfile = NULL, **tmp_metalogfiles;
+    char *dbfiles_path = ctx->rrdeng_ctx->dbfiles_path;
+
+    for (i = 0 ; i < *matched_files ; ++i) {
+        metalogfile = metalogfiles[i];
+        if (0 == metalogfile->starting_fileno)
+            continue; /* skip standard metadata log files */
+        break; /* this is a compaction temporary file */
+    }
+    if (i == *matched_files) /* no recovery needed */
+        return 0;
+    info("Starting metadata log file failure recovery procedure in \"%s\".", dbfiles_path);
+
+    if (*matched_files - i > 1) { /* Can't have more than 1 temporary compaction files */
+        error("Metadata log files are in an invalid state. Cannot proceed.");
+        return 1;
+    }
+    compactionfile = metalogfile;
+    starting_fileno = compactionfile->starting_fileno;
+    fileno = compactionfile->fileno;
+    /* scratchpad space to move file pointers around */
+    tmp_metalogfiles = callocz(*matched_files, sizeof(*tmp_metalogfiles));
+
+    for (j = 0, recovered_files = 0 ; j < i ; ++j) {
+        metalogfile = metalogfiles[j];
+        fatal_assert(0 == metalogfile->starting_fileno);
+        if (metalogfile->fileno < starting_fileno) {
+            tmp_metalogfiles[recovered_files++] = metalogfile;
+            continue;
+        }
+        break; /* reached compaction file serial number */
+    }
+
+    if ((j == i) /* Shouldn't be possible, invalid compaction temporary file */ ||
+        (metalogfile->fileno == starting_fileno && metalogfile->fileno == fileno)) {
+        error("Deleting invalid compaction temporary file \"%s/"METALOG_PREFIX METALOG_FILE_NUMBER_PRINT_TMPL
+              METALOG_EXTENSION"\"", dbfiles_path, starting_fileno, fileno);
+        unlink_metadata_logfile(compactionfile);
+        freez(compactionfile);
+        freez(tmp_metalogfiles);
+        --*matched_files; /* delete the last one */
+
+        info("Finished metadata log file failure recovery procedure in \"%s\".", dbfiles_path);
+        return 0;
+    }
+
+    for ( ; j < i ; ++j) { /* continue iterating through normal metadata log files */
+        metalogfile = metalogfiles[j];
+        fatal_assert(0 == metalogfile->starting_fileno);
+        if (metalogfile->fileno < fileno) { /* It has already been compacted */
+            error("Deleting invalid metadata log file \"%s/"METALOG_PREFIX METALOG_FILE_NUMBER_PRINT_TMPL
+                      METALOG_EXTENSION"\"", dbfiles_path, 0U, metalogfile->fileno);
+            unlink_metadata_logfile(metalogfile);
+            freez(metalogfile);
+            continue;
+        }
+        tmp_metalogfiles[recovered_files++] = metalogfile;
+    }
+
+    /* compaction temporary file is valid */
+    tmp_metalogfiles[recovered_files++] = compactionfile;
+    ret = rename_metadata_logfile(compactionfile, 0, starting_fileno);
+    if (ret < 0) {
+        error("Cannot rename temporary compaction files. Cannot proceed.");
+        freez(tmp_metalogfiles);
+        return 1;
+    }
+
+    memcpy(metalogfiles, tmp_metalogfiles, recovered_files * sizeof(*metalogfiles));
+    *matched_files = recovered_files;
+    freez(tmp_metalogfiles);
+
+    info("Finished metadata log file failure recovery procedure in \"%s\".", dbfiles_path);
+    return 0;
+}