[GEOS-11377] RAT module: allow to reload/recompute the RAT

doc/en/api/1.0.0/rat.yaml

@@ -101,4 +101,33 @@ paths:
         404:
           description: No PAM dataset found
         400:
-          description: Invalid parameters used (e.g., band or classification not found)
+          description: Invalid parameters used (e.g., band or classification not found)
+  /workspaces/{workspace}/coveragestores/{store}/coverages/{coverage}/pam/reload:
+    post:
+      operationId: reloadPAMDataset
+      summary: Reloads/recomputes the PAM dataset
+      description: The PAM is often cached, this operation forces the source to reload it, eventually recomputing it, if for example it's a mosaic with a summary PAM dataset obtained from all its sources
+      tags:
+        - RasterAttributeTable
+      parameters:
+        - name: workspace
+          in: path
+          description: The name of the workspace
+          required: true
+          type: string
+        - name: store
+          in: path
+          description: The name of the coverage datastore
+          required: true
+          type: string
+        - name: coverage
+          in: path
+          description: The name of the coverage
+          required: true
+          type: string
+      responses:
+        200:
+          description: OK
+        404:
+          description: No PAM dataset found
+

src/extension/rat/src/main/java/org/geoserver/rat/rest/PAMController.java

@@ -23,7 +23,10 @@
 import org.geoserver.rest.RestBaseController;
 import org.geoserver.rest.RestException;
 import org.geoserver.rest.catalog.AbstractCatalogController;
+import org.geotools.api.data.ResourceInfo;
 import org.geotools.api.style.Style;
+import org.geotools.coverage.grid.io.GridCoverage2DReader;
+import org.geotools.coverage.grid.io.PAMResourceInfo;
 import org.geotools.util.logging.Logging;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatus;
@@ -68,6 +71,20 @@ public String getRasterAttributeTable(
 
     private CoverageRATs getRATSupport(
             String workspaceName, String storeName, String coverageName) {
+        CoverageInfo coverage = getCoverageInfo(workspaceName, storeName, coverageName);
+
+        CoverageRATs rats = new CoverageRATs(catalog, coverage);
+        if (rats.getPAMDataset() == null) {
+            throw new ResourceNotFoundException(
+                    format(
+                            "No PAMDataset found for coverage: '%s:%s'",
+                            workspaceName, coverageName));
+        }
+        return rats;
+    }
+
+    private CoverageInfo getCoverageInfo(
+            String workspaceName, String storeName, String coverageName) {
         WorkspaceInfo wsInfo = catalog.getWorkspaceByName(workspaceName);
         if (wsInfo == null) {
             // could not find the namespace associated with the desired workspace
@@ -88,15 +105,7 @@ private CoverageRATs getRATSupport(
             throw new ResourceNotFoundException(
                     format("No such coverage: '%s' in store '%s'", coverageName, storeName));
         }
-
-        CoverageRATs rats = new CoverageRATs(catalog, coverage);
-        if (rats.getPAMDataset() == null) {
-            throw new ResourceNotFoundException(
-                    format(
-                            "No PAMDataset found for coverage: '%s:%s'",
-                            workspaceName, coverageName));
-        }
-        return rats;
+        return coverage;
     }
 
     @PostMapping
@@ -161,4 +170,30 @@ public ResponseEntity create(
         return new ResponseEntity<>(
                 "", headers, exists ? HttpStatus.SEE_OTHER : HttpStatus.CREATED);
     }
+
+    @PostMapping(path = "/reload")
+    public void reload(
+            @PathVariable String workspaceName,
+            @PathVariable String storeName,
+            @PathVariable String coverageName)
+            throws IOException {
+        CoverageInfo ci = getCoverageInfo(workspaceName, storeName, coverageName);
+        GridCoverage2DReader reader =
+                (GridCoverage2DReader) ci.getStore().getGridCoverageReader(null, null);
+        ResourceInfo resourceInfo = reader.getInfo(ci.getNativeCoverageName());
+        if (!(resourceInfo instanceof PAMResourceInfo)) {
+            throw new RestException(
+                    format(
+                            "No Raster Attribute Table found for coverage '%s:%s'",
+                            workspaceName, coverageName),
+                    HttpStatus.BAD_REQUEST);
+        }
+        PAMResourceInfo pamInfo = (PAMResourceInfo) resourceInfo;
+        // if the reload does not work, a clear should help (e.g. with GeoTIFF)
+        // as the PAM is normally cached in memory. The mosaic is the odd case that
+        // needs the full reload, as it caches the summary PAM from all its sources
+        if (!pamInfo.reloadPAMDataset()) {
+            catalog.getResourcePool().clear(ci);
+        }
+    }
 }

src/extension/rat/src/test/java/org/geoserver/rat/rest/PAMControllerTest.java

@@ -84,6 +84,44 @@ public void testGetPAMDataset() throws Exception {
                 "1", "count(/PAMDataset/PAMRasterBand/GDALRasterAttributeTable)", doc);
     }
 
+    @Test
+    public void testReloadPAMDataset() throws Exception {
+        MockHttpServletResponse response =
+                getAsServletResponse(
+                        "rest/workspaces/cite/coveragestores/rat/coverages/rat/pam.xml");
+        assertEquals(200, response.getStatus());
+        assertThat(response.getContentType(), Matchers.startsWith("application/xml"));
+        Document doc = dom(getBinaryInputStream(response));
+        // check the first entry has green color
+        assertXpathEvaluatesTo(
+                "green",
+                "/PAMDataset/PAMRasterBand/GDALRasterAttributeTable/Row[@index=0]/F[3]",
+                doc);
+
+        // copy over a RAT with a different color
+        GeoServerDataDirectory dd = getDataDirectory();
+        Resource aux = dd.get("rat", "rat.tiff.aux.xml");
+        Class<RasterAttributeTableConfigTest> clazz = RasterAttributeTableConfigTest.class;
+        try (InputStream is = clazz.getResourceAsStream("rat.tiff.aux2.xml");
+                OutputStream os = aux.out()) {
+            IOUtils.copy(is, os);
+            os.close();
+        }
+
+        // force reload
+        response =
+                postAsServletResponse(
+                        "rest/workspaces/cite/coveragestores/rat/coverages/rat/pam/reload", "");
+        assertEquals(200, response.getStatus());
+
+        // grab again and check color
+        doc = getAsDOM("rest/workspaces/cite/coveragestores/rat/coverages/rat/pam.xml");
+        assertXpathEvaluatesTo(
+                "olive",
+                "/PAMDataset/PAMRasterBand/GDALRasterAttributeTable/Row[@index=0]/F[3]",
+                doc);
+    }
+
     @Test
     public void testCreateStyle() throws Exception {
         String createCommand =

src/extension/rat/src/test/resources/org/geoserver/rat/web/rat.tiff.aux2.xml

@@ -0,0 +1,70 @@
+<PAMDataset>
+  <PAMRasterBand band="1">
+    <Description>Elevation</Description>
+    <UnitType>m</UnitType>
+    <GDALRasterAttributeTable tableType="thematic">
+      <FieldDefn index="0">
+        <Name>con_min</Name>
+        <Type>1</Type>
+        <Usage>3</Usage>
+      </FieldDefn>
+      <FieldDefn index="1">
+        <Name>con_max</Name>
+        <Type>1</Type>
+        <Usage>4</Usage>
+      </FieldDefn>
+      <FieldDefn index="2">
+        <Name>test</Name>
+        <Type>2</Type>
+        <Usage>0</Usage>
+      </FieldDefn>
+      <Row index="0">
+        <F>1.000000023841858</F>
+        <F>1.200000023841858</F>
+        <F>olive</F>
+      </Row>
+      <Row index="1">
+        <F>1.4</F>
+        <F>1.6</F>
+        <F>white</F>
+      </Row>
+      <Row index="2">
+        <F>2.4</F>
+        <F>2.6</F>
+        <F>gold</F>
+      </Row>
+      <Row index="3">
+        <F>5.099999809265137</F>
+        <F>5.299999809265136</F>
+        <F>blue</F>
+      </Row>
+      <Row index="4">
+        <F>7.200000190734864</F>
+        <F>7.400000190734863</F>
+        <F>red</F>
+      </Row>
+      <Row index="5">
+        <F>9.000000381469727</F>
+        <F>9.200000381469726</F>
+        <F>orange</F>
+      </Row>
+      <Row index="6">
+        <F>11.00000038146973</F>
+        <F>11.20000038146973</F>
+        <F>black</F>
+      </Row>
+      <Row index="7">
+        <F>12.09999980926514</F>
+        <F>12.29999980926514</F>
+        <F>purple</F>
+      </Row>
+    </GDALRasterAttributeTable>
+    <Metadata>
+      <MDI key="STATISTICS_MAXIMUM">12.199999809265</MDI>
+      <MDI key="STATISTICS_MEAN">6.2500000745058</MDI>
+      <MDI key="STATISTICS_MINIMUM">1.1000000238419</MDI>
+      <MDI key="STATISTICS_STDDEV">4.0681691852786</MDI>
+      <MDI key="STATISTICS_VALID_PERCENT">100</MDI>
+    </Metadata>
+  </PAMRasterBand>
+</PAMDataset>