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#[cfg(test)]
#[allow(dead_code)]
extern crate growthring;
use growthring::wal::{WALFile, WALStore, WALPos, WALBytes};
use std::collections::{HashMap, hash_map::Entry};
use std::cell::RefCell;
use std::rc::Rc;
/*
thread_local! {
//pub static RNG: RefCell<rand::rngs::StdRng> = RefCell::new(<rand::rngs::StdRng as rand::SeedableRng>::from_seed([0; 32]));
pub static RNG: RefCell<rand::rngs::ThreadRng> = RefCell::new(rand::thread_rng());
}
pub fn gen_rand_letters(i: usize) -> String {
//let mut rng = rand::thread_rng();
RNG.with(|rng| {
(0..i).map(|_| (rng.borrow_mut().gen::<u8>() % 26 + 'a' as u8) as char).collect()
})
}
*/
struct FileContentEmul(RefCell<Vec<u8>>);
impl FileContentEmul {
pub fn new() -> Self { FileContentEmul(RefCell::new(Vec::new())) }
}
impl std::ops::Deref for FileContentEmul {
type Target = RefCell<Vec<u8>>;
fn deref(&self) -> &Self::Target {&self.0}
}
pub trait FailGen {
fn next_fail(&self) -> bool;
}
/// Emulate the a virtual file handle.
pub struct WALFileEmul<G: FailGen> {
file: Rc<FileContentEmul>,
fgen: Rc<G>
}
impl<G: FailGen> WALFile for WALFileEmul<G> {
fn allocate(&self, offset: WALPos, length: usize) -> Result<(), ()> {
if self.fgen.next_fail() { return Err(()) }
let offset = offset as usize;
if offset + length > self.file.borrow().len() {
self.file.borrow_mut().resize(offset + length, 0)
}
for v in &mut self.file.borrow_mut()[offset..offset + length] { *v = 0 }
Ok(())
}
fn truncate(&self, length: usize) -> Result<(), ()> {
if self.fgen.next_fail() { return Err(()) }
self.file.borrow_mut().resize(length, 0);
Ok(())
}
fn write(&self, offset: WALPos, data: WALBytes) -> Result<(), ()> {
if self.fgen.next_fail() { return Err(()) }
let offset = offset as usize;
&self.file.borrow_mut()[offset..offset + data.len()].copy_from_slice(&data);
Ok(())
}
fn read(&self, offset: WALPos, length: usize) -> Result<Option<WALBytes>, ()> {
if self.fgen.next_fail() { return Err(()) }
let offset = offset as usize;
let file = self.file.borrow();
if offset + length > file.len() { Ok(None) }
else {
Ok(Some((&file[offset..offset + length]).to_vec().into_boxed_slice()))
}
}
}
pub struct WALStoreEmulState {
files: HashMap<String, Rc<FileContentEmul>>,
}
impl WALStoreEmulState {
pub fn new() -> Self { WALStoreEmulState { files: HashMap::new() } }
}
/// Emulate the persistent storage state.
pub struct WALStoreEmul<'a, G: FailGen> {
state: &'a mut WALStoreEmulState,
fgen: Rc<G>
}
impl<'a, G: FailGen> WALStoreEmul<'a, G> {
pub fn new(state: &'a mut WALStoreEmulState, fail_gen: G) -> Self {
WALStoreEmul { state, fgen: Rc::new(fail_gen) }
}
}
impl<'a, G: 'static + FailGen> WALStore for WALStoreEmul<'a, G> {
type FileNameIter = std::vec::IntoIter<String>;
fn open_file(&mut self, filename: &str, touch: bool) -> Result<Box<dyn WALFile>, ()> {
if self.fgen.next_fail() { return Err(()) }
match self.state.files.entry(filename.to_string()) {
Entry::Occupied(e) => Ok(Box::new(WALFileEmul {
file: e.get().clone(),
fgen: self.fgen.clone()
})),
Entry::Vacant(e) => if touch {
Ok(Box::new(WALFileEmul {
file: e.insert(Rc::new(FileContentEmul::new())).clone(),
fgen: self.fgen.clone()
}))
} else {
Err(())
}
}
}
fn remove_file(&mut self, filename: &str) -> Result<(), ()> {
if self.fgen.next_fail() { return Err(()) }
self.state.files.remove(filename).ok_or(()).and_then(|_| Ok(()))
}
fn enumerate_files(&self) -> Result<Self::FileNameIter, ()> {
if self.fgen.next_fail() { return Err(()) }
let mut logfiles = Vec::new();
for (fname, _) in self.state.files.iter() {
logfiles.push(fname.clone())
}
Ok(logfiles.into_iter())
}
fn apply_payload(&mut self, payload: WALBytes) -> Result<(), ()> {
if self.fgen.next_fail() { return Err(()) }
println!("apply_payload(payload={})", std::str::from_utf8(&payload).unwrap());
Ok(())
}
}
pub struct SingleFailGen {
cnt: std::cell::Cell<usize>,
fail_point: usize
}
impl SingleFailGen {
pub fn new(fail_point: usize) -> Self {
SingleFailGen {
cnt: std::cell::Cell::new(0),
fail_point
}
}
}
impl FailGen for SingleFailGen {
fn next_fail(&self) -> bool {
let c = self.cnt.get();
self.cnt.set(c + 1);
c == self.fail_point
}
}
pub struct ZeroFailGen;
impl FailGen for ZeroFailGen {
fn next_fail(&self) -> bool { false }
}
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