[Caching] Add CAS size management APIs

Sources/CSwiftScan/include/swiftscan_header.h

@@ -274,6 +274,13 @@ typedef struct {
 
   //=== Scanner CAS Operations ----------------------------------------------===//
   swiftscan_cas_options_t (*swiftscan_cas_options_create)(void);
+  int64_t (*swiftscan_cas_get_ondisk_size)(swiftscan_cas_t,
+                                           swiftscan_string_ref_t *error);
+  bool (*swiftscan_cas_set_ondisk_size_limit)(swiftscan_cas_t,
+                                              int64_t size_limit,
+                                              swiftscan_string_ref_t *error);
+  bool (*swiftscan_cas_prune_ondisk_data)(swiftscan_cas_t,
+                                          swiftscan_string_ref_t *error);
   void (*swiftscan_cas_options_dispose)(swiftscan_cas_options_t options);
   void (*swiftscan_cas_options_set_ondisk_path)(swiftscan_cas_options_t options,
                                                 const char *path);

Sources/SwiftDriver/SwiftScan/SwiftScan.swift

@@ -300,6 +300,17 @@ internal extension swiftscan_diagnostic_severity_t {
 #endif
   }
 
+  @_spi(Testing) public var supportsCASSizeManagement : Bool {
+#if os(Windows)
+    // CAS is currently not supported on Windows hosts.
+    return false
+#else
+    return api.swiftscan_cas_get_ondisk_size != nil &&
+           api.swiftscan_cas_set_ondisk_size_limit != nil &&
+           api.swiftscan_cas_prune_ondisk_data != nil
+#endif
+  }
+
   @_spi(Testing) public var supportsBridgingHeaderPCHCommand : Bool {
     return api.swiftscan_swift_textual_detail_get_bridging_pch_command_line != nil
   }
@@ -511,6 +522,9 @@ private extension swiftscan_functions_t {
     self.swiftscan_cas_options_set_plugin_option = try loadOptional("swiftscan_cas_options_set_plugin_option")
     self.swiftscan_cas_options_dispose = try loadOptional("swiftscan_cas_options_dispose")
     self.swiftscan_cas_create_from_options = try loadOptional("swiftscan_cas_create_from_options")
+    self.swiftscan_cas_get_ondisk_size = try loadOptional("swiftscan_cas_get_ondisk_size")
+    self.swiftscan_cas_set_ondisk_size_limit = try loadOptional("swiftscan_cas_set_ondisk_size_limit")
+    self.swiftscan_cas_prune_ondisk_data = try loadOptional("swiftscan_cas_prune_ondisk_data")
     self.swiftscan_cas_dispose = try loadOptional("swiftscan_cas_dispose")
     self.swiftscan_cache_compute_key = try loadOptional("swiftscan_cache_compute_key")
     self.swiftscan_cache_compute_key_from_input_index = try loadOptional("swiftscan_cache_compute_key_from_input_index")

Sources/SwiftDriver/SwiftScan/SwiftScanCAS.swift

@@ -198,6 +198,29 @@ public final class SwiftScanCAS {
     return try scanner.toSwiftString(casid)
   }
 
+  public var supportsSizeManagement: Bool {
+    scanner.supportsCASSizeManagement
+  }
+
+  public func getStorageSize() throws -> Int64? {
+    let size = try scanner.handleCASError { err_msg in
+      scanner.api.swiftscan_cas_get_ondisk_size(cas, &err_msg)
+    }
+    return size == -1 ? nil : size
+  }
+
+  public func setSizeLimit(_ size: Int64) throws {
+    _ = try scanner.handleCASError { err_msg in
+      scanner.api.swiftscan_cas_set_ondisk_size_limit(cas, size, &err_msg)
+    }
+  }
+
+  public func prune() throws {
+    _ = try scanner.handleCASError { err_msg in
+      scanner.api.swiftscan_cas_prune_ondisk_data(cas, &err_msg)
+    }
+  }
+
   @available(*, deprecated)
   public func computeCacheKey(commandLine: [String], input: String) throws -> String {
     let casid = try scanner.handleCASError { err_msg in

Tests/SwiftDriverTests/CachingBuildTests.swift

@@ -849,4 +849,27 @@ final class CachingBuildTests: XCTestCase {
       }
     }
   }
+
+  func testCASManagement() throws {
+    try withTemporaryDirectory { path in
+      let casPath = path.appending(component: "cas")
+      let driver = try Driver(args: ["swiftc", "-v"])
+      let scanLibPath = try XCTUnwrap(driver.getSwiftScanLibPath())
+      try dependencyOracle.verifyOrCreateScannerInstance(fileSystem: localFileSystem,
+                                                         swiftScanLibPath: scanLibPath)
+      let cas = try dependencyOracle.getOrCreateCAS(pluginPath: nil, onDiskPath: casPath, pluginOptions: [])
+      guard cas.supportsSizeManagement else {
+        throw XCTSkip("CAS size management is not supported")
+      }
+      let preSize = try XCTUnwrap(try cas.getStorageSize())
+      let dataToStore = Data(count: 1000)
+      _ = try cas.store(data: dataToStore)
+      let postSize = try XCTUnwrap(try cas.getStorageSize())
+      XCTAssertTrue(postSize > preSize)
+
+      // Try prune.
+      try cas.setSizeLimit(100)
+      try cas.prune()
+    }
+  }
 }