Add simple program to drop files from the buffer cache.

4 files changed, 36 insertions, 0 deletions

diff --git a/vespalib/CMakeLists.txt b/vespalib/CMakeLists.txt
index b32c875cb26..2212bbeb57a 100644
--- a/vespalib/CMakeLists.txt
+++ b/vespalib/CMakeLists.txt
@@ -12,6 +12,7 @@ vespa_define_module(
     src/apps/make_fixture_macros
     src/apps/vespa-detect-hostname
     src/apps/vespa-validate-hostname
+    src/apps/vespa-drop-file-from-cache
 
     TESTS
     src/tests/alignedmemory
diff --git a/vespalib/src/apps/vespa-drop-file-from-cache/.gitignore b/vespalib/src/apps/vespa-drop-file-from-cache/.gitignore
new file mode 100644
index 00000000000..24dc558b6bc
--- /dev/null
+++ b/vespalib/src/apps/vespa-drop-file-from-cache/.gitignore
@@ -0,0 +1 @@
+vespa-drop-file-from-cache
diff --git a/vespalib/src/apps/vespa-drop-file-from-cache/CMakeLists.txt b/vespalib/src/apps/vespa-drop-file-from-cache/CMakeLists.txt
new file mode 100644
index 00000000000..409fd5bb725
--- /dev/null
+++ b/vespalib/src/apps/vespa-drop-file-from-cache/CMakeLists.txt
@@ -0,0 +1,9 @@
+# Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+vespa_add_executable(vespalib_vespa-drop-file-from-cache_app
+    SOURCES
+    drop_file_from_cache.cpp
+    OUTPUT_NAME vespa-drop-file-from-cache
+    INSTALL bin
+    DEPENDS
+    vespalib
+)
diff --git a/vespalib/src/apps/vespa-drop-file-from-cache/drop_file_from_cache.cpp b/vespalib/src/apps/vespa-drop-file-from-cache/drop_file_from_cache.cpp
new file mode 100644
index 00000000000..eca88c83738
--- /dev/null
+++ b/vespalib/src/apps/vespa-drop-file-from-cache/drop_file_from_cache.cpp
@@ -0,0 +1,25 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+#include <cstdio>
+#include <fcntl.h>
+#include <unistd.h>
+
+int main(int argc, char **argv) {
+    if (argc != 2) {
+        fprintf(stderr, "%s <filename>", argv[0]);
+        return 1;
+    }
+    const char *fileName = argv[1];
+    int fh = open(fileName, O_RDONLY);
+    if (fh != -1) {
+        int err = posix_fadvise(fh, 0, 0, POSIX_FADV_DONTNEED);
+        if (err != 0) {
+            perror("posix_fadvise failed");
+        }
+        close(fh);
+    } else {
+        perror("Failed opening file");
+        return 1;
+    }
+    return 0;
+}