Remove ability to switch between snapshot implementations

Signed-off-by: mdouglas47 <[email protected]>

Author: morgando

db/comdb2.c

@@ -462,9 +462,6 @@ int gbl_enable_berkdb_retry_deadlock_bias = 0;
 int gbl_enable_cache_internal_nodes = 1;
 int gbl_use_modsnap_for_snapshot = 0;
 int gbl_modsnap_asof = 0;
-const snap_impl_enum gbl_snap_fallback_impl = SNAP_IMPL_MODSNAP;
-const snap_impl_enum gbl_snap_backup_fallback_impl = SNAP_IMPL_MODSNAP;
-snap_impl_enum gbl_snap_impl = SNAP_IMPL_MODSNAP;
 int gbl_rep_process_txn_time = 0;
 int gbl_utxnid_log = 1;
 int gbl_test_commit_lsn_map = 0;

db/comdb2.h

@@ -3429,12 +3429,6 @@ enum { TCM_PARENT_DEADLOCK = 1, TCM_MAX = 1 };
 /* tagged api big or little endian. */
 enum { TAGGED_API_BIG_ENDIAN = 1, TAGGED_API_LITTLE_ENDIAN = 2 };
 
-typedef enum {
-    SNAP_IMPL_ORIG,
-    SNAP_IMPL_NEW,
-    SNAP_IMPL_MODSNAP,
-} snap_impl_enum;
-
 extern int gbl_check_schema_change_permissions;
 
 extern int gbl_support_datetime_in_triggers;

db/config.c

@@ -58,9 +58,6 @@ extern int gbl_disable_new_snapshot;
 extern int gbl_server_admin_mode;
 extern int gbl_modsnap_asof;
 extern int gbl_use_modsnap_for_snapshot;
-extern const snap_impl_enum gbl_snap_fallback_impl;
-extern const snap_impl_enum gbl_snap_backup_fallback_impl;
-extern snap_impl_enum gbl_snap_impl;
 
 int gbl_disable_access_controls;
 
@@ -73,7 +70,6 @@ static int gbl_nogbllrl; /* don't load /bb/bin/comdb2*.lrl */
 
 static int pre_read_option(char *, int);
 static int read_lrl_option(struct dbenv *, char *, struct read_lrl_option_type *, int, int *);
-static void fallback_from_snap_impl();
 
 // clang-format off
 static struct option long_options[] = {
@@ -629,10 +625,6 @@ static struct dbenv *read_lrl_file_int(struct dbenv *dbenv, const char *lrlname,
 
     /* process legacy options (we deferred them) */
 
-    if (gbl_disable_new_snapshot && (gbl_snap_impl == SNAP_IMPL_NEW)) {
-        fallback_from_snap_impl();
-    }
-
     if (gbl_rowlocks) {
         /* We can't ever choose a writer as a deadlock victim in rowlocks mode
            (at least without some kludgery, or snapshots) */
@@ -719,110 +711,6 @@ static int new_table_from_schema(struct dbenv *dbenv, char *tblname,
     return 0;
 }
 
-/*
- * Toggles the 'modsnap' snapshot implementation on and off.
- *
- * switch_val: 1 if toggling on and 0 if toggling off.
- */
-static void toggle_modsnap(int switch_val) {
-    gbl_use_modsnap_for_snapshot = switch_val;
-    gbl_modsnap_asof = switch_val;
-}
-
-/*
- * Toggles the 'new' snapshot implementation on and off.
- *
- * switch_val: 1 if toggling on and 0 if toggling off.
- */
-static void toggle_new_snapisol(int switch_val) {
-    gbl_new_snapisol = switch_val;
-    gbl_new_snapisol_asof = switch_val;
-    gbl_new_snapisol_logging = switch_val;
-}
-
-/*
- * Prints a string representation of a `snap_impl_enum` type,
- * or "UNKNOWN" if the value passed in is not a valid `snap_impl_enum`.
- *
- * impl: The value to output as a string.
- */
-const char *snap_impl_str(snap_impl_enum impl) {
-    switch (impl) {
-    case SNAP_IMPL_ORIG:
-        return "ORIGINAL";
-        break;
-    case SNAP_IMPL_NEW:
-        return "NEW";
-        break;
-    case SNAP_IMPL_MODSNAP:
-        return "MODSNAP";
-        break;
-    default:
-        return "UNKNOWN";
-        break;
-    }
-}
-
-static const char * value_on_off(int switch_var) {
-    const char * value = switch_var ? "ON" : "OFF";
-    return value;
-}
-
-void print_snap_config(loglvl lvl) {
-    logmsg(lvl, "Snapshot is %s; "
-                "Implementation set to '%s'; "
-                "gbl_use_modsnap_for_snapshot=%s; "
-                "gbl_modsnap_asof=%s; "
-                "gbl_new_snapisol=%s; "
-                "gbl_new_snapisol_asof=%s; "
-                "gbl_new_snapisol_logging=%s\n",
-                value_on_off(gbl_snapisol),
-                snap_impl_str(gbl_snap_impl),
-                value_on_off(gbl_use_modsnap_for_snapshot),
-                value_on_off(gbl_modsnap_asof),
-                value_on_off(gbl_new_snapisol),
-                value_on_off(gbl_new_snapisol_asof),
-                value_on_off(gbl_new_snapisol_logging));
-}
-
-/*
- * Sets the snapshot implementation.
- *
- * impl: The implementation to be set.
- */
-void set_snapshot_impl(snap_impl_enum impl) {
-    gbl_snap_impl = impl;
-    gbl_snap_impl == SNAP_IMPL_MODSNAP ? toggle_modsnap(1) : toggle_modsnap(0);
-    gbl_snap_impl == SNAP_IMPL_NEW ? toggle_new_snapisol(1) : toggle_new_snapisol(0);
-}
-
-/*
- * Determines what the fallback implementation should be for the current
- * snapshot implementation and switches to it.
- */
-static void fallback_from_snap_impl() {
-    const snap_impl_enum fallback_impl = 
-        gbl_snap_fallback_impl != gbl_snap_impl ? gbl_snap_fallback_impl : gbl_snap_backup_fallback_impl;
-
-    assert(fallback_impl != gbl_snap_impl);
-    set_snapshot_impl(fallback_impl);
-}
-
-/*
- * Enables snapshot isolation.
- *
- * dbenv: Parent environment.
- */
-static void enable_snapshot(struct dbenv *dbenv) {
-    if (gbl_snapisol) {
-        return;
-    }
-
-    set_snapshot_impl(gbl_snap_impl); 
-    bdb_attr_set(dbenv->bdb_attr, BDB_ATTR_SNAPISOL, 1);
-    gbl_snapisol = 1;
-}
-
 #define parse_lua_funcs(pfx)                                                                                           \
     do {                                                                                                               \
         tok = segtok(line, strlen(line), &st, &ltok);                                                                  \
@@ -1372,18 +1260,10 @@ static int read_lrl_option(struct dbenv *dbenv, char *line,
         bdb_attr_set(dbenv->bdb_attr, BDB_ATTR_SNAPISOL, 1);
         logmsg(LOGMSG_INFO, "Enabled logical logging\n");
     } else if (tokcmp(tok, ltok, "enable_snapshot_isolation") == 0) {
-        enable_snapshot(dbenv);
-    } else if (tokcmp(tok, ltok, "enable_new_snapshot") == 0 ||
-               tokcmp(tok, ltok, "enable_new_snapshot_asof") == 0) {
-        set_snapshot_impl(SNAP_IMPL_NEW);
-        enable_snapshot(dbenv);
-    } else if (tokcmp(tok, ltok, "enable_new_snapshot_logging") == 0) {
         bdb_attr_set(dbenv->bdb_attr, BDB_ATTR_SNAPISOL, 1);
-        gbl_new_snapisol_logging = 1;
-        logmsg(LOGMSG_INFO, "Enabled new snapshot logging\n");
-    } else if (tokcmp(tok, ltok, "disable_new_snapshot") == 0) {
-        gbl_disable_new_snapshot = 1;
-        logmsg(LOGMSG_INFO, "Disabled new snapshot\n");
+        gbl_snapisol = 1;
+        gbl_use_modsnap_for_snapshot = 1;
+        gbl_modsnap_asof = 1;
     } else if (tokcmp(tok, ltok, "enable_serial_isolation") == 0) {
         bdb_attr_set(dbenv->bdb_attr, BDB_ATTR_SNAPISOL, 1);
         gbl_snapisol = 1;
@@ -1679,10 +1559,6 @@ static int read_lrl_option(struct dbenv *dbenv, char *line,
         }
     }
 
-    if (gbl_disable_new_snapshot && (gbl_snap_impl == SNAP_IMPL_NEW)) {
-        fallback_from_snap_impl();
-    }
-
     if (gbl_rowlocks) {
         /* We can't ever choose a writer as a deadlock victim in rowlocks mode
            (at least without some kludgery, or snapshots) */

db/db_tunables.c

@@ -172,7 +172,6 @@ extern int gbl_udp;
 extern int gbl_update_delete_limit;
 extern int gbl_updategenids;
 extern int gbl_use_modsnap_for_snapshot;
-extern snap_impl_enum gbl_snap_impl;
 extern int gbl_use_node_pri;
 extern int gbl_watchdog_watch_threshold;
 extern int portmux_port;
@@ -595,9 +594,6 @@ extern int gbl_nonodh_queue_scan_limit;
 extern int gbl_sql_row_delay_msecs;
 extern int gbl_thread_wait_sec;
 
-extern void set_snapshot_impl(snap_impl_enum impl);
-extern const char *snap_impl_str(snap_impl_enum impl);
-
 int64_t gbl_driver_ulimit = 0;
 
 int gbl_test_tunable_nozero = 1;
@@ -671,49 +667,6 @@ int percent_verify(void *unused, void *percent)
     return 0;
 }
 
-struct snapshot_impl_config_st {
-    const char *name;
-    int code;
-} snapshot_impl_config_vals[] = {{"original", SNAP_IMPL_ORIG},
-                                {"new", SNAP_IMPL_NEW},
-                                {"modsnap", SNAP_IMPL_MODSNAP}};
-
-static int snapshot_impl_update(void *context, void *value) {
-    comdb2_tunable *tunable;
-    char *tok;
-    int st = 0;
-    int ltok;
-    int len;
-    int rc;
-
-    tunable = (comdb2_tunable *)context;
-    len = strlen(value);
-    tok = segtok(value, len, &st, &ltok);
-    rc = 0;
-
-    for (int i = 0; i < (sizeof(snapshot_impl_config_vals) /
-                         sizeof(struct snapshot_impl_config_st));
-         i++) {
-        if (tokcmp(tok, ltok, snapshot_impl_config_vals[i].name) == 0) {
-            set_snapshot_impl(snapshot_impl_config_vals[i].code);
-            goto found;
-        }
-    }
-
-    logmsg(LOGMSG_ERROR, "Invalid value '%s' for tunable '%s'\n", tok, tunable->name);
-    rc = 1;
-
-found:
-    return rc;
-}
-
-static void *snapshot_impl_value(void *context)
-{
-    comdb2_tunable *tunable = (comdb2_tunable *)context;
-
-    return (void *) snap_impl_str(*(int *)tunable->var);
-}
-
 struct enable_sql_stmt_caching_st {
     const char *name;
     int code;

db/db_tunables.h

@@ -232,12 +232,6 @@ REGISTER_TUNABLE("disable_inplace_blobs", "Disables 'enable_inplace_blobs'",
 REGISTER_TUNABLE("disable_lowpri_snapisol", "Disables 'enable_lowpri_snapisol'",
                  TUNABLE_BOOLEAN, &gbl_lowpri_snapisol_sessions,
                  INVERSE_VALUE | READONLY | NOARG, NULL, NULL, NULL, NULL);
-/*
-REGISTER_TUNABLE("disable_new_snapshot",
-                 "Disables 'enable_new_snapshot'", TUNABLE_BOOLEAN,
-                 &gbl_new_snapisol, INVERSE_VALUE | READONLY | NOARG, NULL,
-                 NULL, NULL, NULL);
-*/
 REGISTER_TUNABLE("disable_osql_blob_optimization",
                  "Disables 'enable_osql_blob_optimization'", TUNABLE_BOOLEAN,
                  &gbl_osql_blob_optimization, INVERSE_VALUE | READONLY | NOARG,
@@ -461,22 +455,6 @@ REGISTER_TUNABLE("enable_lowpri_snapisol",
                  "state. (Default: off)",
                  TUNABLE_BOOLEAN, &gbl_lowpri_snapisol_sessions,
                  READONLY | NOARG, NULL, NULL, NULL, NULL);
-
-/*
-REGISTER_TUNABLE("enable_new_snapshot",
-                 "Enable new SNAPSHOT implementation. (Default: off)",
-                 TUNABLE_BOOLEAN, &gbl_new_snapisol, READONLY | NOARG, NULL,
-                 NULL, NULL, NULL);
-REGISTER_TUNABLE(
-    "enable_new_snapshot_asof",
-    "Enable new BEGIN TRANSACTION AS OF implementation. (Default: off)",
-    TUNABLE_BOOLEAN, &gbl_new_snapisol_asof, READONLY | NOARG, NULL, NULL, NULL,
-    NULL);
-REGISTER_TUNABLE("enable_new_snapshot_logging",
-                 "Enable alternate logging scheme. (Default: off)",
-                 TUNABLE_BOOLEAN, &gbl_new_snapisol_logging, READONLY | NOARG,
-                 NULL, NULL, NULL, NULL);
-*/
 REGISTER_TUNABLE("enable_osql_blob_optimization",
                  "Replicant tracks which columns are modified in a transaction "
                  "to allow blob updates to be ommitted if possible. (Default: "
@@ -511,11 +489,6 @@ REGISTER_TUNABLE("enable_serial_isolation",
                  "the database. (Default: off)",
                  TUNABLE_BOOLEAN, &gbl_serializable, NOARG | READONLY, NULL, NULL, NULL,
                  NULL);
-REGISTER_TUNABLE("set_snapshot_impl",
-                 "Changes the default snapshot implementation "
-                 "*without enabling snapshot* (default 'modsnap')",
-                 TUNABLE_ENUM, &gbl_snap_impl, READEARLY | READONLY,
-                 snapshot_impl_value, NULL, snapshot_impl_update, NULL);
 REGISTER_TUNABLE("use_current_lsn_for_non_snapshot",
                  "comdb2_snapshot_lsn provide current LSN if not using snapshot isolation. (Default: off)",
                  TUNABLE_BOOLEAN, &gbl_use_current_lsn_for_non_snapshot, INTERNAL | EXPERIMENTAL, NULL, NULL, NULL,

db/process_message.c

@@ -222,7 +222,6 @@ static const char *HELP_STAT[] = {
     "stat mtrap                 - show mtrap system stats",
     "stat dohsql                - show distributed sql stats",
     "stat oldfile               - dump oldfile hash",
-    "stat snapconfig            - print snapshot configuration information",
     "dmpl                       - dump threads",
     "dmptrn                     - show long transaction stats",
     "dmpcts                     - show table constraints",
@@ -2007,8 +2006,6 @@ int process_command(struct dbenv *dbenv, char *line, int lline, int st)
             oldfile_dump();
         } else if (tokcmp(tok, ltok, "ssl") == 0) {
             ssl_stats();
-        } else if (tokcmp(tok, ltok, "snapconfig") == 0) {
-            print_snap_config(LOGMSG_USER);
         } else {
             int rc = 1;
             struct message_handler *h;

docs/pages/config/config_files.md

@@ -805,7 +805,6 @@ These options are toggle-able at runtime.
 |disable_inplace_blob_optimization | | Disables enable_inplace_blob_optimization
 |disable_inplace_blobs | | Disables enable_inplace_blobs (needs enable_inplace_blob_optimization, and enable_osql_blob_optimization also enabled - which they are by default)
 |disable_lowpri_snapisol | |
-|disable_new_snapshot | | Disables alternate snapshot implementation
 |disable_osql_blob_optimization | | Disables disable_osql_blob_optimization
 |disable_overflow_page_trace | 1 | If set, warn when a page order table scan encounters an overflow page.
 |disable_page_latches | | Turns off page latches
@@ -828,9 +827,6 @@ These options are toggle-able at runtime.
 |enable_inplace_blob_optimization | | Enables inplace blob updates (blobs are updated in place in their b-tree when possible, not deleted/added)
 |enable_inplace_blobs | set | Don't update the rowid of a blob entry on an update 
 |enable_lowpri_snapisol | 0 | Give lower priority to locks acquired when updating snapshot state 
-|enable_new_snapshot | 0 | ***Experimental*** Enable new SNAPSHOT implementation
-|enable_new_snapshot_asof | 0 | ***Experimental*** Enable new BEGIN TRANSACTION AS OF implementation
-|enable_new_snapshot_logging | 0 | ***Experimental*** Enable alternate logging scheme 
 |enable_osql_blob_optimization | set | Replicant tracks which columns are modified in a transaction to allow blob updates to be omitted if possible
 |enable_overflow_page_trace | | If set, don't warn when a page order table scan encounters an overflow page.
 |enable_pageorder_recsz_check | | Disables enable_pageorder_recsz_check

docs/pages/operating/op.md

@@ -919,10 +919,6 @@ Display key compression information.
 
 Display root page cache information.
 
-### stat snapconfig
-
-Prints out snapshot configuration information.
-
 ### Other stats
 
 Various other commands can also be run prepended with stat: [stax](#stax), [long](#long), [stal](#stal), [thr](#thr), [dmpl](#dmpl).