src/Pure/General/file_store.scala

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Pure/General/file_store.scala	Wed Feb 12 15:22:47 2025 +0100
@@ -0,0 +1,133 @@
+/*  Title:      Pure/General/file_store.scala
+    Author:     Makarius
+
+Persistent store for file-system content, backed by SQL database
+(notably SQLite).
+*/
+
+package isabelle
+
+
+import java.io.{File => JFile}
+
+
+object File_Store {
+  /* main operations */
+
+  def make_database(database: Path, dir: Path,
+    pred: JFile => Boolean = _ => true,
+    name_prefix: String = "",
+    compress_options: Compress.Options = Compress.Options(),
+    compress_cache: Compress.Cache = Compress.Cache.none
+  ): Unit = {
+    database.file.delete()
+    using(SQLite.open_database(database)) { db =>
+      private_data.transaction_lock(db, create = true) {
+        val root = dir.canonical_file
+        val root_path = File.path(root)
+        for {
+          file <- File.find_files(root, pred = pred)
+          rel_path <- File.relative_path(root_path, File.path(file))
+        } {
+          val entry =
+            Entry.read_file(rel_path, name_prefix = name_prefix, dir = root_path,
+              compress_options = compress_options, compress_cache = compress_cache)
+          private_data.write_entry(db, entry)
+        }
+      }
+    }
+  }
+
+  def database_entry(database: Path, name: String): Option[Entry] =
+    if (!database.is_file) None
+    else {
+      using(SQLite.open_database(database)) { db =>
+        private_data.transaction_lock(db) {
+          if (!private_data.tables.forall(db.exists_table)) None
+          else private_data.read_entry(db, name)
+        }
+      }
+    }
+
+
+  /* entry */
+
+  object Entry {
+    def read_file(path: Path,
+      name_prefix: String = "",
+      dir: Path = Path.current,
+      compress_options: Compress.Options = Compress.Options(),
+      compress_cache: Compress.Cache = Compress.Cache.none
+    ): Entry = {
+      val name = Url.append_path(name_prefix, path.expand.implode)
+      val bs = Bytes.read(dir + path)
+      val size = bs.size
+      val executable = File.is_executable(dir + path)
+      val (compressed, body) = bs.maybe_compress(options = compress_options, cache = compress_cache)
+      Entry(name, size, executable, compressed, body)
+    }
+  }
+
+  sealed case class Entry(
+    name: String,
+    size: Long,
+    executable: Boolean,
+    compressed: Boolean,
+    body: Bytes
+  ) {
+    require(name.nonEmpty && size >= 0 && (size > 0 || compressed))
+
+    def content(cache: Compress.Cache = Compress.Cache.none): Bytes =
+      if (compressed) body.uncompress(cache = cache) else body
+
+    def write_file(dir: Path, cache: Compress.Cache = Compress.Cache.none): Unit = {
+      val path = Path.explode(name)
+      File.content(path, content(cache = cache)).write(dir)
+      if (executable) File.set_executable(dir + path)
+    }
+  }
+
+
+  /* SQL data model */
+
+  object private_data extends SQL.Data() {
+    override lazy val tables: SQL.Tables = SQL.Tables(Base.table)
+
+    object Base {
+      val name = SQL.Column.string("name").make_primary_key
+      val size = SQL.Column.long("size")
+      val executable = SQL.Column.bool("executable")
+      val compressed = SQL.Column.bool("compressed")
+      val body = SQL.Column.bytes("body")
+
+      val table = SQL.Table("isabelle_file_store", List(name, size, executable, compressed, body))
+    }
+
+    def read_names(db: SQL.Database): List[String] =
+      db.execute_query_statement(
+        Base.table.select(List(Base.name)),
+        List.from[String], _.string(Base.name)
+      ).sorted
+
+    def read_entry(db: SQL.Database, name: String): Option[Entry] =
+      db.execute_query_statementO[Entry](
+        Base.table.select(List(Base.size, Base.executable, Base.compressed, Base.body),
+          sql = Base.name.where_equal(name)),
+        { res =>
+          val size = res.long(Base.size)
+          val executable = res.bool(Base.executable)
+          val compressed = res.bool(Base.compressed)
+          val body = res.bytes(Base.body)
+          Entry(name, size, executable, compressed, body)
+        })
+
+    def write_entry(db: SQL.Database, entry: Entry): Unit =
+      db.execute_statement(Base.table.insert(), body = { stmt =>
+        stmt.string(1) = entry.name
+        stmt.long(2) = entry.size
+        stmt.bool(3) = entry.executable
+        stmt.bool(4) = entry.compressed
+        stmt.bytes(5) = entry.body
+      })
+  }
+}