[7.x][ML] Remove model snapshot legacy doc ids (elastic#62434)

Removes methods that were no longer used regarding version 5.4 doc ids of ModelState.

Also adds clean up of 5.4 model state and quantile docs in the daily maintenance.

Backport of elastic#62434

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/job/process/autodetect/state/ModelSnapshot.java

@@ -21,8 +21,8 @@
 import org.elasticsearch.common.xcontent.XContentFactory;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.common.xcontent.XContentType;
-import org.elasticsearch.xpack.core.ml.job.config.Job;
 import org.elasticsearch.xpack.core.common.time.TimeUtils;
+import org.elasticsearch.xpack.core.ml.job.config.Job;
 
 import java.io.IOException;
 import java.io.InputStream;
@@ -287,18 +287,6 @@ public List<String> stateDocumentIds() {
         return stateDocumentIds;
     }
 
-    /**
-     * This is how the IDs were formed in v5.4
-     */
-    public List<String> legacyStateDocumentIds() {
-        List<String> stateDocumentIds = new ArrayList<>(snapshotDocCount);
-        // The state documents count suffices are 1-based
-        for (int i = 1; i <= snapshotDocCount; i++) {
-            stateDocumentIds.add(ModelState.v54DocumentId(jobId, snapshotId, i));
-        }
-        return stateDocumentIds;
-    }
-
     public static String documentIdPrefix(String jobId) {
         return jobId + "_" + TYPE + "_";
     }

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/job/process/autodetect/state/ModelState.java

@@ -6,37 +6,48 @@
 package org.elasticsearch.xpack.core.ml.job.process.autodetect.state;
 
 
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
 /**
  * The model state does not need to be understood on the Java side.
  * The Java code only needs to know how to form the document IDs so that
  * it can retrieve and delete the correct documents.
  */
-public class ModelState {
+public final class ModelState {
 
     /**
      * Legacy type, now used only as a discriminant in the document ID
      */
     public static final String TYPE = "model_state";
 
-    public static final String documentId(String jobId, String snapshotId, int docNum) {
-        return jobId + "_" + TYPE + "_" + snapshotId + "#" + docNum;
-    }
+    private static final Pattern V_5_4_DOC_ID_REGEX = Pattern.compile("(.*)-\\d{10}#\\d+");
 
-    /**
-     * This is how the IDs were formed in v5.4
-     */
-    public static final String v54DocumentId(String jobId, String snapshotId, int docNum) {
-        return jobId + "-" + snapshotId + "#" + docNum;
+    public static String documentId(String jobId, String snapshotId, int docNum) {
+        return jobId + "_" + TYPE + "_" + snapshotId + "#" + docNum;
     }
 
     /**
      * Given the id of a state document it extracts the job id
      * @param docId the state document id
      * @return the job id or {@code null} if the id is not valid
      */
-    public static final String extractJobId(String docId) {
+    public static String extractJobId(String docId) {
         int suffixIndex = docId.lastIndexOf("_" + TYPE + "_");
-        return suffixIndex <= 0 ? null : docId.substring(0, suffixIndex);
+        return suffixIndex <= 0 ? v54ExtractJobId(docId) : docId.substring(0, suffixIndex);
+    }
+
+    /**
+     * On version 5.4 the state doc ids had a different pattern.
+     * The pattern started with the job id, followed by a hyphen, the snapshot id,
+     * and ended with hash and an integer.
+     */
+    private static String v54ExtractJobId(String docId) {
+        Matcher matcher = V_5_4_DOC_ID_REGEX.matcher(docId);
+        if (matcher.matches()) {
+            return matcher.group(1);
+        }
+        return null;
     }
 
     private ModelState() {

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/job/process/autodetect/state/Quantiles.java

@@ -65,8 +65,13 @@ public static String v54DocumentId(String jobId) {
      * @param docId the quantiles document id
      * @return the job id or {@code null} if the id is not valid
      */
-    public static final String extractJobId(String docId) {
+    public static String extractJobId(String docId) {
         int suffixIndex = docId.lastIndexOf("_" + TYPE);
+        return suffixIndex <= 0 ? v54extractJobId(docId) : docId.substring(0, suffixIndex);
+    }
+
+    private static String v54extractJobId(String docId) {
+        int suffixIndex = docId.lastIndexOf("-" + TYPE);
         return suffixIndex <= 0 ? null : docId.substring(0, suffixIndex);
     }
 

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/job/process/autodetect/state/ModelStateTests.java

@@ -28,4 +28,13 @@ public void testExtractJobId_GivenInvalidDocId() {
         assertThat(ModelState.extractJobId("_model_state_3141341341"), is(nullValue()));
         assertThat(ModelState.extractJobId("foo_quantiles"), is(nullValue()));
     }
-}
+
+    public void testExtractJobId_GivenV54DocId() {
+        assertThat(ModelState.extractJobId("test_job_id-1-0123456789#1"), equalTo("test_job_id-1"));
+        assertThat(ModelState.extractJobId("test_job_id-2-9876543210#42"), equalTo("test_job_id-2"));
+        assertThat(ModelState.extractJobId("test_job_id-0123456789-9876543210#42"), equalTo("test_job_id-0123456789"));
+
+        // This one has one less digit for snapshot id
+        assertThat(ModelState.extractJobId("test_job_id-123456789#42"), is(nullValue()));
+    }
+}

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/job/process/autodetect/state/QuantilesTests.java

@@ -28,6 +28,13 @@ public void testExtractJobId_GivenValidDocId() {
         assertThat(Quantiles.extractJobId("_quantiles_quantiles"), equalTo("_quantiles"));
     }
 
+    public void testExtractJobId_GivenV54DocId() {
+        assertThat(Quantiles.extractJobId("foo-quantiles"), equalTo("foo"));
+        assertThat(Quantiles.extractJobId("bar-quantiles"), equalTo("bar"));
+        assertThat(Quantiles.extractJobId("foo-bar-quantiles"), equalTo("foo-bar"));
+        assertThat(Quantiles.extractJobId("-quantiles-quantiles"), equalTo("-quantiles"));
+    }
+
     public void testExtractJobId_GivenInvalidDocId() {
         assertThat(Quantiles.extractJobId(""), is(nullValue()));
         assertThat(Quantiles.extractJobId("foo"), is(nullValue()));

x-pack/plugin/ml/src/test/java/org/elasticsearch/xpack/ml/utils/MlStringsTests.java

@@ -34,6 +34,7 @@ public void testIsValidId() {
         assertThat(MlStrings.isValidId("b.-_3"), is(true));
         assertThat(MlStrings.isValidId("a-b.c_d"), is(true));
 
+        assertThat(MlStrings.isValidId("1_-.a#"), is(false));
         assertThat(MlStrings.isValidId("a1_-."), is(false));
         assertThat(MlStrings.isValidId("-.a1_"), is(false));
         assertThat(MlStrings.isValidId(".a1_-"), is(false));