Auto merge of #99 - TheNeikos:add-libstore, r=matthiasbeyer

Add libimagstore

Alright, do check the file and feel free to post comments/ask questions

Cargo.lock

@@ -8,6 +8,30 @@ dependencies = [
  "libimagutil 0.1.0",
 ]
 
+[[package]]
+name = "fs2"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "kernel32-sys 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "kernel32-sys"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "winapi 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi-build 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "libimagmodule"
 version = "0.1.0"
@@ -19,8 +43,35 @@ version = "0.1.0"
 [[package]]
 name = "libimagstore"
 version = "0.1.0"
+dependencies = [
+ "fs2 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "toml 0.1.25 (registry+https://github.com/rust-lang/crates.io-index)",
+]
 
 [[package]]
 name = "libimagutil"
 version = "0.1.0"
 
+[[package]]
+name = "rustc-serialize"
+version = "0.3.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "toml"
+version = "0.1.25"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "rustc-serialize 0.3.16 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "winapi"
+version = "0.2.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "winapi-build"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+

doc/src/04000-lib-store.md

@@ -4,3 +4,67 @@
     Store functionality
 -->
 
+The "libstore" MUST define the programming-language level interface to the
+store on the file system.
+The library therefor MUST define and export types which can be used to get data
+from the filesystem.
+
+## Types {#sec:libstore:types}
+
+The types in @tbl:libstore:types are exported by the library.
+
+| Type          | Meaning                                          |
+| :------------ | :----------------------------------------------- |
+| Entry         | Entity on the Filesystem, File                   |
+| EntryContent  | User-Content of the Entry                        |
+| EntryHeader   | Header of the Entry                              |
+| Store         | Store interface                                  |
+| FileLockEntry | Handle to an Entry                               |
+
+Table: Types the store library exports {#tbl:libstore:types}
+
+Each of these types MUST export functions to work with the data the objects of
+the types contain.
+
+### Entry {#sec:libstore:types:entry}
+
+The `Entry` type MUST hold the following content:
+
+- A path where on the filesystem the acutal file lives
+- An instance of `EntryContent` as interface to the content of the file
+  (@sec:libstore:types:entrycontent).
+- An instance of `EntryHeader` as interface to the header of the file
+  (@sec:libstore:types:entryheader).
+
+The entry type MUST export functions to get
+
+- The content object
+- The header object
+- The path of the actual file
+
+The entry type MUST export functions to set
+
+- The header object
+- The content object
+
+### EntryContent {#sec:libstore:types:entrycontent}
+
+The `EntryContent` type is an type-alias for `String`.
+
+### EntryHeader {#sec:libstore:types:entryheader}
+
+The `EntryHeader` type is an wrapper around the type, the TOML-Parser library
+exports.
+
+It SHOULD contain utility functions to work with the header in a convenient way.
+
+### Store {#sec:libstore:types:store}
+
+The `Store` type MUST represent the interface to the store on the filesystem.
+It MUST contain CRUD-functionality to work with the entries in the store.
+It MUST contain a variable which contains the path of the store on the
+filesystem which is represented by an object of this type.
+It also MUST contain a getter for this variable.
+It MUST NOT contain a setter for this variable, as changing the store while the
+programm is running is not allowed.
+

libimagstore/Cargo.lock

@@ -1,4 +1,55 @@
 [root]
 name = "libimagstore"
 version = "0.1.0"
+dependencies = [
+ "fs2 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "toml 0.1.25 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "fs2"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "kernel32-sys 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "kernel32-sys"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "winapi 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi-build 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "rustc-serialize"
+version = "0.3.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "toml"
+version = "0.1.25"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "rustc-serialize 0.3.16 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "winapi"
+version = "0.2.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "winapi-build"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
 

libimagstore/Cargo.toml

@@ -2,3 +2,9 @@
 name = "libimagstore"
 version = "0.1.0"
 authors = ["Matthias Beyer <mail@beyermatthias.de>"]
+
+[dependencies]
+
+fs2 = "0.2.2"
+toml = "0.1.25"
+

libimagstore/src/content.rs

@@ -0,0 +1 @@
+pub type EntryContent = String;

libimagstore/src/entry.rs

@@ -0,0 +1,11 @@
+use header::EntryHeader;
+use content::EntryContent;
+use store::StoreId;
+
+#[derive(Debug, Clone)]
+pub struct Entry {
+    location: StoreId,
+    header: EntryHeader,
+    content: EntryContent,
+}
+

libimagstore/src/error.rs

@@ -0,0 +1,77 @@
+use std::error::Error;
+use std::fmt::Debug;
+use std::fmt::Display;
+use std::fmt::Formatter;
+use std::fmt::Error as FmtError;
+use std::clone::Clone;
+use std::convert::From;
+
+use std::io::Error as IOError;
+
+#[derive(Clone, Copy, Debug)]
+pub enum StoreErrorKind {
+    IdNotFound,
+    OutOfMemory,
+    // maybe more
+}
+
+fn store_error_type_as_str(e: &StoreErrorKind) -> &'static str {
+    match e {
+        &StoreErrorKind::IdNotFound  => "ID not found",
+        &StoreErrorKind::OutOfMemory => "Out of Memory",
+    }
+}
+
+impl Display for StoreErrorKind {
+
+    fn fmt(&self, fmt: &mut Formatter) -> Result<(), FmtError> {
+        try!(write!(fmt, "{}", store_error_type_as_str(self)));
+        Ok(())
+    }
+
+}
+
+#[derive(Debug)]
+pub struct StoreError {
+    err_type: StoreErrorKind,
+    cause: Option<Box<Error>>,
+}
+
+impl StoreError {
+
+    pub fn new(errtype: StoreErrorKind, cause: Option<Box<Error>>)
+        -> StoreError
+    {
+        StoreError {
+            err_type: errtype,
+            cause: cause,
+        }
+    }
+
+    pub fn err_type(&self) -> StoreErrorKind {
+        self.err_type.clone()
+    }
+
+}
+
+impl Display for StoreError {
+
+    fn fmt(&self, fmt: &mut Formatter) -> Result<(), FmtError> {
+        try!(write!(fmt, "[{}]", store_error_type_as_str(&self.err_type.clone())));
+        Ok(())
+    }
+
+}
+
+impl Error for StoreError {
+
+    fn description(&self) -> &str {
+        store_error_type_as_str(&self.err_type.clone())
+    }
+
+    fn cause(&self) -> Option<&Error> {
+        self.cause.as_ref().map(|e| &**e)
+    }
+
+}
+

libimagstore/src/header.rs

@@ -0,0 +1,20 @@
+use toml::Table;
+
+#[derive(Debug, Clone)]
+pub struct EntryHeader {
+    toml: Table,
+}
+
+impl EntryHeader {
+
+    pub fn new(toml: Table) -> EntryHeader {
+        EntryHeader {
+            toml: toml,
+        }
+    }
+
+    pub fn toml(&self) -> &Table {
+        &self.toml
+    }
+
+}

libimagstore/src/lib.rs

@@ -1,3 +1,9 @@
-#[test]
-fn it_works() {
-}
+extern crate fs2;
+extern crate toml;
+
+pub mod content;
+pub mod entry;
+pub mod error;
+pub mod header;
+pub mod store;
+

libimagstore/src/store.rs

@@ -0,0 +1,227 @@
+use std::collections::HashMap;
+use std::fs::File;
+use std::ops::Drop;
+use std::path::PathBuf;
+use std::result::Result as RResult;
+use std::sync::Arc;
+use std::sync::{RwLock, Mutex};
+
+use fs2::FileExt;
+
+use entry::Entry;
+use error::StoreError;
+
+/// The Result Type returned by any interaction with the store that could fail
+pub type Result<T> = RResult<T, StoreError>;
+
+/// The Index into the Store
+pub type StoreId = PathBuf;
+
+/// This Trait allows you to convert various representations to a single one
+/// suitable for usage in the Store
+trait IntoStoreId {
+    fn into_storeid(self) -> StoreId;
+}
+
+impl<'a> IntoStoreId for &'a str {
+    fn into_storeid(self) -> StoreId {
+        PathBuf::from(self)
+    }
+}
+
+impl<'a> IntoStoreId for &'a String{
+    fn into_storeid(self) -> StoreId {
+        PathBuf::from(self)
+    }
+}
+
+impl IntoStoreId for String{
+    fn into_storeid(self) -> StoreId {
+        PathBuf::from(self)
+    }
+}
+
+impl IntoStoreId for PathBuf {
+    fn into_storeid(self) -> StoreId {
+        self
+    }
+}
+
+impl<'a> IntoStoreId for &'a PathBuf {
+    fn into_storeid(self) -> StoreId {
+        self.clone()
+    }
+}
+
+impl<ISI: IntoStoreId> IntoStoreId for (ISI, ISI) {
+    fn into_storeid(self) -> StoreId {
+        let (first, second) = self;
+        let mut res : StoreId = first.into_storeid();
+        res.push(second.into_storeid());
+        res
+    }
+}
+
+#[derive(PartialEq)]
+enum StoreEntryPresence {
+    Present,
+    Borrowed
+}
+
+/// A store entry, depending on the option type it is either borrowed currently
+/// or not.
+struct StoreEntry {
+    file: File,
+    entry: StoreEntryPresence
+}
+
+
+impl StoreEntry {
+    /// The entry is currently borrowed, meaning that some thread is currently
+    /// mutating it
+    fn is_borrowed(&self) -> bool {
+        self.entry == StoreEntryPresence::Borrowed
+    }
+
+    /// Flush the entry to disk
+    fn set_entry(&mut self, entry: Entry) -> Result<()> {
+        unimplemented!()
+    }
+
+    /// We borrow the entry
+    fn get_entry(&mut self) -> Result<Entry> {
+        unimplemented!()
+    }
+
+    /// We copy the entry
+    fn copy_entry(&mut self) -> Result<Entry> {
+        unimplemented!()
+    }
+}
+
+/// The Store itself, through this object one can interact with IMAG's entries
+pub struct Store {
+    location: PathBuf,
+
+    /**
+     * Internal Path->File cache map
+     *
+     * Caches the files, so they remain flock()ed
+     *
+     * Could be optimized for a threadsafe HashMap
+     */
+    entries: Arc<RwLock<HashMap<StoreId, StoreEntry>>>,
+}
+
+impl Store {
+    /// Creates the Entry at the given location (inside the entry)
+    pub fn create(&self, entry: Entry) -> Result<()> {
+        unimplemented!();
+    }
+
+    /// Borrow a given Entry. When the `FileLockEntry` is either `update`d or
+    /// dropped, the new Entry is written to disk
+    pub fn retrieve<'a>(&'a self, id: StoreId) -> Result<FileLockEntry<'a>> {
+        unimplemented!();
+    }
+
+    /// Return the `FileLockEntry` and write to disk
+    pub fn update<'a>(&'a self, entry: FileLockEntry<'a>) -> Result<()> {
+        self._update(&entry)
+    }
+
+    /// Internal method to write to the filesystem store.
+    ///
+    /// # Assumptions
+    /// This method assumes that entry is dropped _right after_ the call, hence
+    /// it is not public.
+    fn _update<'a>(&'a self, entry: &FileLockEntry<'a>) -> Result<()> {
+        unimplemented!();
+    }
+
+    /// Retrieve a copy of a given entry, this cannot be used to mutate
+    /// the one on disk
+    pub fn retrieve_copy(&self, id: StoreId) -> Result<Entry> {
+        unimplemented!();
+    }
+
+    /// Delete an entry
+    pub fn delete(&self, id: StoreId) -> Result<()> {
+        unimplemented!();
+    }
+}
+
+impl Drop for Store {
+
+    /**
+     * Unlock all files on drop
+     *
+     * TODO: Error message when file cannot be unlocked?
+     */
+    fn drop(&mut self) {
+        self.entries.write().unwrap()
+            .iter().map(|f| f.1.file.unlock());
+    }
+
+}
+
+/// A struct that allows you to borrow an Entry
+pub struct FileLockEntry<'a> {
+    store: &'a Store,
+    entry: Entry,
+    key: StoreId,
+}
+
+impl<'a> FileLockEntry<'a, > {
+    fn new(store: &'a Store, entry: Entry, key: StoreId) -> FileLockEntry<'a> {
+        FileLockEntry {
+            store: store,
+            entry: entry,
+            key: key,
+        }
+    }
+}
+
+impl<'a> ::std::ops::Deref for FileLockEntry<'a> {
+    type Target = Entry;
+
+    fn deref(&self) -> &Self::Target {
+        &self.entry
+    }
+}
+
+impl<'a> ::std::ops::DerefMut for FileLockEntry<'a> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.entry
+    }
+}
+
+impl<'a> Drop for FileLockEntry<'a> {
+    fn drop(&mut self) {
+        self.store._update(self).unwrap()
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use std::path::PathBuf;
+    use store::{StoreId, IntoStoreId};
+
+    #[test]
+    fn into_storeid_trait() {
+        let buf = PathBuf::from("abc/def");
+
+        let test = ("abc", "def");
+        assert_eq!(buf, test.into_storeid());
+
+        let test = "abc/def";
+        assert_eq!(buf, test.into_storeid());
+
+        let test = String::from("abc/def");
+        assert_eq!(buf, test.into_storeid());
+
+        let test = PathBuf::from("abc/def");
+        assert_eq!(buf, test.into_storeid());
+    }
+}
+