Avoid calling require('lz4') if it's really not required

This changes the utlity module to return a function instead of the module directly. This way, caller can control when the module is actually tried to be resolved.

Author: ikkala

lib/DBSQLSession.ts

@@ -232,7 +232,7 @@ export default class DBSQLSession implements IDBSQLSession {
     }
 
     if (ProtocolVersion.supportsArrowCompression(this.serverProtocolVersion) && request.canDownloadResult !== true) {
-      request.canDecompressLZ4Result = (options.useLZ4Compression ?? clientConfig.useLZ4Compression) && Boolean(LZ4);
+      request.canDecompressLZ4Result = (options.useLZ4Compression ?? clientConfig.useLZ4Compression) && Boolean(LZ4());
     }
 
     const operationPromise = driver.executeStatement(request);

lib/result/ArrowResultHandler.ts

@@ -26,7 +26,7 @@ export default class ArrowResultHandler implements IResultsProvider<ArrowBatch>
     this.arrowSchema = arrowSchema ?? hiveSchemaToArrowSchema(schema);
     this.isLZ4Compressed = lz4Compressed ?? false;
 
-    if (this.isLZ4Compressed && !LZ4) {
+    if (this.isLZ4Compressed && !LZ4()) {
       throw new HiveDriverError('Cannot handle LZ4 compressed result: module `lz4` not installed');
     }
   }
@@ -52,7 +52,7 @@ export default class ArrowResultHandler implements IResultsProvider<ArrowBatch>
     let totalRowCount = 0;
     rowSet?.arrowBatches?.forEach(({ batch, rowCount }) => {
       if (batch) {
-        batches.push(this.isLZ4Compressed ? LZ4!.decode(batch) : batch);
+        batches.push(this.isLZ4Compressed ? LZ4()!.decode(batch) : batch);
         totalRowCount += rowCount.toNumber(true);
       }
     });

lib/result/CloudFetchResultHandler.ts

@@ -27,7 +27,7 @@ export default class CloudFetchResultHandler implements IResultsProvider<ArrowBa
     this.source = source;
     this.isLZ4Compressed = lz4Compressed ?? false;
 
-    if (this.isLZ4Compressed && !LZ4) {
+    if (this.isLZ4Compressed && !LZ4()) {
       throw new HiveDriverError('Cannot handle LZ4 compressed result: module `lz4` not installed');
     }
   }
@@ -64,7 +64,7 @@ export default class CloudFetchResultHandler implements IResultsProvider<ArrowBa
     }
 
     if (this.isLZ4Compressed) {
-      batch.batches = batch.batches.map((buffer) => LZ4!.decode(buffer));
+      batch.batches = batch.batches.map((buffer) => LZ4()!.decode(buffer));
     }
     return batch;
   }

lib/utils/lz4.ts

@@ -26,4 +26,14 @@ function tryLoadLZ4Module(): LZ4Module | undefined {
   }
 }
 
-export default tryLoadLZ4Module();
+// The null is already tried resolving that failed
+let resolvedModule: LZ4Module | null | undefined;
+
+function getResolvedModule() {
+  if (resolvedModule === undefined) {
+    resolvedModule = tryLoadLZ4Module() ?? null;
+  }
+  return resolvedModule ?? undefined;
+}
+
+export default getResolvedModule;