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-rw-r--r--common/indexeddb.js228
1 files changed, 157 insertions, 71 deletions
diff --git a/common/indexeddb.js b/common/indexeddb.js
index d0bacc4..c6302fa 100644
--- a/common/indexeddb.js
+++ b/common/indexeddb.js
@@ -55,8 +55,8 @@ const nr_reductor = ([i, s], num) => [i - 1, s + num * 1024 ** i];
const version_nr = ver => Array.reduce(ver.slice(0, 3), nr_reductor, [2, 0])[1];
const stores = [
- ["files", {keyPath: "sha256"}],
- ["file_uses", {keyPath: "sha256"}],
+ ["files", {keyPath: "hash_key"}],
+ ["file_uses", {keyPath: "hash_key"}],
["resources", {keyPath: "identifier"}],
["mappings", {keyPath: "identifier"}]
];
@@ -92,7 +92,7 @@ async function idb_del(transaction, store_name, key)
}
/* Open haketilo database, asynchronously return an IDBDatabase object. */
-async function get_db(initialization_data=initial_data)
+async function get_db(data=initial_data)
{
if (db)
return db;
@@ -120,9 +120,9 @@ async function get_db(initialization_data=initial_data)
for (const [store_name, key_mode] of stores)
store = opened_db.createObjectStore(store_name, key_mode);
- await new Promise(resolve => store.transaction.oncomplete = resolve);
+ const context = make_context(store.transaction, data.files);
- save_items(db, initialization_data);
+ await _save_items(data.resources, data.mappings, context);
}
db = opened_db;
@@ -130,6 +130,105 @@ async function get_db(initialization_data=initial_data)
return db;
}
+/* Helper function used by start_items_transaction() and get_db(). */
+function make_context(transaction, files)
+{
+ files = files || {};
+ const context = {transaction, files, file_uses: {}};
+
+ let resolve, reject;
+ context.result = new Promise((...cbs) => [resolve, reject] = cbs);
+
+ context.transaction.oncomplete = resolve;
+ context.transaction.onerror = reject;
+
+ return context;
+}
+
+/*
+ * item_store_names should be an array with either string "mappings", string
+ * "resources" or both. files should be a dict with values being contents of
+ * files that are to be possibly saved in this transaction and keys of the form
+ * `sha256-<file's-sha256-sum>`.
+ *
+ * Returned is a context object wrapping the transaction and handling the
+ * counting of file references in IndexedDB.
+ */
+async function start_items_transaction(item_store_names, files)
+{
+ const db = await haketilodb.get();
+ const scope = [...item_store_names, "files", "file_uses"];
+ return make_context(db.transaction(scope, "readwrite"), files);
+}
+
+async function incr_file_uses(context, file_ref, by=1)
+{
+ const hash_key = file_ref.hash_key;
+ let uses = context.file_uses[hash_key];
+ if (uses === undefined) {
+ uses = await idb_get(context.transaction, "file_uses", hash_key);
+ if (uses)
+ [uses.new, uses.initial] = [false, uses.uses];
+ else
+ uses = {hash_key, uses: 0, new: true, initial: 0};
+
+ context.file_uses[hash_key] = uses;
+ }
+
+ uses.uses = uses.uses + by;
+}
+
+const decr_file_uses = (ctx, file_ref) => incr_file_uses(ctx, file_ref, -1);
+
+async function finalize_items_transaction(context)
+{
+ for (const uses of Object.values(context.file_uses)) {
+ if (uses.uses < 0)
+ console.error("internal error: uses < 0 for file " + uses.hash_key);
+
+ const is_new = uses.new;
+ const initial_uses = uses.initial;
+ const hash_key = uses.hash_key;
+
+ delete uses.new;
+ delete uses.initial;
+
+ if (uses.uses < 1) {
+ if (!is_new) {
+ idb_del(context.transaction, "file_uses", hash_key);
+ idb_del(context.transaction, "files", hash_key);
+ }
+
+ continue;
+ }
+
+ if (uses.uses === initial_uses)
+ continue;
+
+ idb_put(context.transaction, "file_uses", uses);
+
+ if (initial_uses > 0)
+ continue;
+
+ const file = context.files[hash_key];
+ if (file === undefined) {
+ context.transaction.abort();
+ throw "file not present: " + hash_key;
+ }
+
+ idb_put(context.transaction, "files", {hash_key, contents: file});
+ }
+
+ return context.result;
+}
+
+async function with_items_transaction(cb, item_store_names, files={})
+{
+ const context = await start_items_transaction(item_store_names, files);
+ await cb(context);
+ await finalize_items_transaction(context);
+}
+
/*
* How a sample data argument to the function below might look like:
*
@@ -167,97 +266,84 @@ async function get_db(initialization_data=initial_data)
* }
* }
*/
-async function save_items(db, data)
+async function save_items(transaction, data)
{
- const files = data.files;
- const resources =
- Object.values(data.resources || []).map(entities.get_newest);
- const mappings =
- Object.values(data.mappings || []).map(entities.get_newest);
+ const items_store_names = ["resources", "mappings"];
+ const context = start_items_transaction(items_store_names, data.files);
- resources.concat(mappings).forEach(i => save_item(i, data.files, db));
+ return _save_items(data.resources, data.mappings, context);
}
-/* helper function of save_item() */
-async function get_file_uses(transaction, file_uses_sha256, file_ref)
+async function _save_items(resources, mappings, context)
{
- let uses = file_uses_sha256[file_ref.sha256];
- if (uses === undefined) {
- uses = await idb_get(transaction, "file_uses", file_ref.sha256);
- if (uses)
- [uses.new, uses.initial] = [false, uses.uses];
- else
- uses = {sha256: file_ref.sha256, uses: 0, new: true, initial: 0};
+ resources = Object.values(resources || {}).map(entities.get_newest);
+ mappings = Object.values(mappings || {}).map(entities.get_newest);
- file_uses_sha256[file_ref.sha256] = uses;
- }
+ for (const item of resources.concat(mappings))
+ await save_item(item, context);
- return uses;
+ await finalize_items_transaction(context);
}
/*
* Save given definition of a resource/mapping to IndexedDB. If the definition
* (passed as `item`) references files that are not already present in
* IndexedDB, those files should be present as values of the `files_sha256`
- * object with keys being their sha256 sums.
+ * object with keys being of the form `sha256-<file's-sha256-sum>`.
+ *
+ * context should be one returned from start_items_transaction() and should be
+ * later passed to finalize_items_transaction() so that files depended on are
+ * added to IndexedDB and files that are no longer depended on after this
+ * operation are removed from IndexedDB.
*/
-async function save_item(item, files_sha256, db)
+async function save_item(item, context)
{
const store_name = {resource: "resources", mapping: "mappings"}[item.type];
- const transaction =
- db.transaction([store_name, "files", "file_uses"], "readwrite");
-
- let resolve, reject;
- const result = new Promise((...cbs) => [resolve, reject] = cbs);
- transaction.oncomplete = resolve;
- transaction.onerror = reject;
- const uses_sha256 = {};
for (const file_ref of entities.get_files(item))
- (await get_file_uses(transaction, uses_sha256, file_ref)).uses++;
+ await incr_file_uses(context, file_ref);
- const old_item = await idb_get(transaction, store_name, item.identifier);
- if (old_item !== undefined) {
- for (const file_ref of entities.get_files(old_item))
- (await get_file_uses(transaction, uses_sha256, file_ref)).uses--;
- }
-
- for (const uses of Object.values(uses_sha256)) {
- if (uses.uses < 0)
- console.error("internal error: uses < 0 for file " + uses.sha256);
-
- const [is_new, initial_uses] = [uses.new, uses.initial];
- delete uses.new;
- delete uses.initial;
-
- if (uses.uses < 1) {
- if (!is_new) {
- idb_del(transaction, "file_uses", uses.sha256);
- idb_del(transaction, "files", uses.sha256);
- }
-
- continue;
- }
-
- if (uses.uses === initial_uses)
- continue;
-
- const file = files_sha256[uses.sha256];
- if (file === undefined)
- throw "file not present: " + uses.sha256;
+ await _remove_item(store_name, item.identifier, context, false);
+ await idb_put(context.transaction, store_name, item);
+}
- idb_put(transaction, "files", {sha256: uses.sha256, contents: file});
- idb_put(transaction, "file_uses", uses);
+/* Helper function used by remove_item() and save_item(). */
+async function _remove_item(store_name, identifier, context)
+{
+ const item = await idb_get(context.transaction, store_name, identifier);
+ if (item !== undefined) {
+ for (const file_ref of entities.get_files(item))
+ await decr_file_uses(context, file_ref);
}
+}
- idb_put(transaction, store_name, item);
-
- return result;
+/*
+ * Remove definition of a resource/mapping from IndexedDB.
+ *
+ * context should be one returned from start_items_transaction() and should be
+ * later passed to finalize_items_transaction() so that files depended on are
+ * added to IndexedDB and files that are no longer depended on after this
+ * operation are removed from IndexedDB.
+ */
+async function remove_item(store_name, identifier, context)
+{
+ await _remove_item(store_name, identifier, context);
+ await idb_del(context.transaction, store_name, identifier);
}
+const remove_resource =
+ (identifier, ctx) => remove_item("resources", identifier, ctx);
+const remove_mapping =
+ (identifier, ctx) => remove_item("mappings", identifier, ctx);
+
const haketilodb = {
- get: get_db,
- save_item: save_item
+ get: get_db,
+ save_items,
+ save_item,
+ remove_resource,
+ remove_mapping,
+ start_items_transaction,
+ finalize_items_transaction
};
/*