implement read only open (#4)

dice-group · Sep 25, 2023 · 31963c5 · 31963c5
1 parent 5ea2906
commit 31963c5
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Showing 3 changed files with 67 additions and 19 deletions.
diff --git a/src/dice/ffi/metall.cpp b/src/dice/ffi/metall.cpp
@@ -3,15 +3,16 @@
 
 using metall_manager_t = dice::metall_ffi::internal::metall_manager;
 
-metall_manager *metall_open(char const *path) {
+template<auto open_mode>
+metall_manager *open_impl(char const *path) {
     if (!metall::manager::consistent(path)) {
         // prevents opening the same datastore twice
         // (because opening removes the properly_closed_mark and this checks for it)
         errno = ENOTRECOVERABLE;
         return nullptr;
     }
 
-    auto *manager = new metall_manager_t{metall::open_only, path};
+    auto *manager = new metall_manager_t{open_mode, path};
     if (!manager->check_sanity()) {
         delete manager;
         errno = ENOTRECOVERABLE;
@@ -21,6 +22,14 @@ metall_manager *metall_open(char const *path) {
     return reinterpret_cast<metall_manager *>(manager);
 }
 
+metall_manager *metall_open(char const *path) {
+    return open_impl<metall::open_only>(path);
+}
+
+metall_manager *metall_open_read_only(char const *path) {
+    return open_impl<metall::open_read_only>(path);
+}
+
 metall_manager *metall_create(char const *path) {
     if (std::filesystem::exists(path)) {
         // prevent accidental overwrite

diff --git a/src/dice/ffi/metall.h b/src/dice/ffi/metall.h
@@ -18,6 +18,14 @@ typedef struct metall_manager metall_manager;
  */
 metall_manager *metall_open(char const *path);
 
+/**
+ * @brief Attempts to open the metall datastore at path in read only mode
+ * @param path path to datastore
+ * @return true on success, false on failure. On failure, sets errno to one of the following values:
+ *      - ENOTRECOVERABLE if the given metall datastore is inconsistent
+ */
+metall_manager *metall_open_read_only(char const *path);
+
 /**
  * @brief Attempts to create a metall datastore at path
  * @param path path at which to create a datastore

diff --git a/tests/tests_Sanity.cpp b/tests/tests_Sanity.cpp
@@ -18,12 +18,30 @@ TEST_SUITE("metall-ffi") {
                 FAIL("failed to create: ", strerror(errno));
             }
 
-            auto *ptr = static_cast<size_t *>(metall_malloc(manager, obj_name, sizeof(size_t)));
+            {
+                auto *ptr = static_cast<size_t *>(metall_malloc(manager, obj_name, sizeof(size_t)));
+                CHECK_NE(ptr, nullptr);
+                CHECK_EQ(reinterpret_cast<uintptr_t>(ptr) % alignof(size_t), 0);
+
+                *ptr = 55;
+                CHECK_EQ(*ptr, 55);
+            }
+
+            metall_close(manager);
+        }
+
+        {
+            metall_manager *manager = metall_open(path.c_str());
+            if (manager == nullptr) {
+                FAIL("failed to create: ", strerror(errno));
+            }
+
+            auto *ptr = static_cast<size_t *>(metall_find(manager, obj_name));
             CHECK_NE(ptr, nullptr);
             CHECK_EQ(reinterpret_cast<uintptr_t>(ptr) % alignof(size_t), 0);
 
-            *ptr = 55;
-            CHECK_EQ(*ptr, 55);
+            *ptr = 66;
+            CHECK_EQ(*ptr, 66);
 
             if (!metall_snapshot(manager, snap_path.c_str())) {
                 FAIL("failed to snapshot: ", strerror(errno));
@@ -33,26 +51,39 @@ TEST_SUITE("metall-ffi") {
         }
 
         auto check = [obj_name](auto const &path) {
-            metall_manager *manager = metall_open(path.c_str());
-            if (manager == nullptr) {
-                FAIL("failed to open: ", strerror(errno));
-            }
+            {
+                metall_manager *manager = metall_open_read_only(path.c_str());
+                if (manager == nullptr) {
+                    FAIL("failed to open: ", strerror(errno));
+                }
 
-            auto *ptr = static_cast<size_t *>(metall_find(manager, obj_name));
-            if (ptr == nullptr) {
-                FAIL("failed to load: ", strerror(errno));
-            }
+                auto *ptr = static_cast<size_t *>(metall_find(manager, obj_name));
+                if (ptr == nullptr) {
+                    FAIL("failed to load: ", strerror(errno));
+                }
 
-            CHECK_EQ(*ptr, 55);
+                CHECK_EQ(*ptr, 66);
 
-            if (!metall_free(manager, obj_name)) {
-                FAIL("failed to dealloc: ", strerror(errno));
+                CHECK_FALSE(metall_free(manager, obj_name));
+
+                metall_close(manager);
             }
 
-            metall_close(manager);
+            {
+                metall_manager *manager = metall_open(path.c_str());
+                if (manager == nullptr) {
+                    FAIL("failed to open: ", strerror(errno));
+                }
+
+                if (!metall_free(manager, obj_name)) {
+                    FAIL("failed to dealloc: ", strerror(errno));
+                }
 
-            CHECK(metall_remove(path.c_str()));
-            CHECK(!metall_open(path.c_str()));
+                metall_close(manager);
+
+                CHECK(metall_remove(path.c_str()));
+                CHECK(!metall_open(path.c_str()));
+            }
         };
 
         check(snap_path);