1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294
use std::path::PathBuf; use std::time::SystemTime; /// The base watchable trait. pub trait Watchable { /// The path associated with the watchable object fn path(&self) -> &PathBuf; } /// A standalone implementation of the watchable trait. #[derive(Debug, Clone)] pub struct BasicTarget { /// The path we want to watch path: PathBuf, } impl BasicTarget { pub fn new<T: Into<PathBuf>>(path: T) -> Self { Self { path: path.into() } } } impl Watchable for BasicTarget { fn path(&self) -> &PathBuf { &self.path } } #[derive(Debug, Copy, Clone, Eq, PartialEq)] /// State transitions that a watchable may undergo. pub enum Transition { Created, Modified, Deleted, None, } #[derive(Debug, Eq, PartialEq)] /// The current state of the watchable. pub enum WatchState { DoesNotExist, Exists(Option<SystemTime>), } #[derive(Debug, Default)] /// A watcher instance. /// /// An instance of Watcher keeps track of a vector of watchables and their corresponding states. pub struct Watcher<W: Watchable> { targets: Vec<W>, states: Vec<WatchState>, } fn compute_state<W: Watchable>(target: &W) -> WatchState { // Does the specified path exist let file_exists = target.path().exists(); // Compute the last modification date of this file, if possible let mut last_modified_date = None; if file_exists { // Determine the last modification time of this file let metadata = std::fs::metadata(target.path()); if let Ok(metadata) = metadata { if let Ok(modified) = metadata.modified() { last_modified_date = Some(modified); } } } if file_exists { WatchState::Exists(last_modified_date) } else { WatchState::DoesNotExist } } impl<W: Watchable> Watcher<W> { /// Create a new watcher instance. /// /// # Examples /// /// ``` /// use fwatch::{BasicTarget, Watcher}; /// /// fn main() { /// let mut watcher: Watcher<BasicTarget> = Watcher::new(); /// } /// ``` pub fn new() -> Self { Watcher { targets: Vec::new(), states: Vec::new(), } } /// Adds a target to the watcher. /// /// # Examples /// /// ``` /// use fwatch::{BasicTarget, Watcher}; /// /// fn main() { /// let mut watcher : Watcher<BasicTarget> = Watcher::new(); /// /// // Watch the "foo.txt" path /// watcher.add_target(BasicTarget::new("foo.txt")); /// } /// ``` pub fn add_target(&mut self, target: W) { self.states.push(compute_state(&target)); self.targets.push(target); } /// Remove a target from the watcher. /// /// This function will panic if index is greater than the size of self.states() / self.targets(). /// /// # Examples /// /// ``` /// use fwatch::{BasicTarget, Watcher}; /// /// fn main() { /// let mut watcher : Watcher<BasicTarget> = Watcher::new(); /// /// // Inserts "foo.txt" at index 0 /// watcher.add_target(BasicTarget::new("foo.txt")); /// /// // Remove "foo.txt" from the watcher /// assert!(watcher.remove_target(0)); /// } /// ``` pub fn remove_target(&mut self, index: usize) -> bool { if index > self.states.len() { false } else { self.states.remove(index); self.targets.remove(index); true } } /// Attempt to get the state corresponding to the given target index. /// /// Note that this doesn't update the current state. /// /// # Examples /// /// ```no_run /// use fwatch::{BasicTarget, Watcher, WatchState}; /// /// fn main() { /// let mut watcher : Watcher<BasicTarget> = Watcher::new(); /// /// // Watch a file that doesn't exist /// watcher.add_target(BasicTarget::new("does_not_exist.txt")); /// assert_eq!(watcher.get_state(0).unwrap(), &WatchState::DoesNotExist); /// /// // Watch a file that does exist /// watcher.add_target(BasicTarget::new("exists.txt")); /// assert_ne!(watcher.get_state(1).unwrap(), &WatchState::DoesNotExist); /// } /// ``` pub fn get_state(&self, index: usize) -> Option<&WatchState> { self.states.get(index) } /// Attempt to get the path corresponding to the given target index. /// /// # Examples /// /// ``` /// use fwatch::{BasicTarget, Watcher, WatchState}; /// /// fn main() { /// let mut watcher : Watcher<BasicTarget> = Watcher::new(); /// watcher.add_target(BasicTarget::new("foo.txt")); /// /// let path = watcher.get_path(0).unwrap(); /// assert_eq!(path.to_str().unwrap(), "foo.txt"); /// } /// ``` pub fn get_path(&self, index: usize) -> Option<&PathBuf> { self.targets.get(index).and_then(|v| Some(v.path())) } /// Observe any state transitions in our targets. /// /// Returns a vector containing the observed state transition for each target. /// /// # Examples /// /// ``` /// use fwatch::{BasicTarget, Watcher, Transition}; /// /// fn main() { /// let mut watcher : Watcher<BasicTarget> = Watcher::new(); /// /// // Watch a file that doesn't exist /// watcher.add_target(BasicTarget::new("does_not_exist.txt")); /// /// let results = watcher.watch(); /// /// for (index, transition) in watcher.watch().into_iter().enumerate() { /// // Get a reference to the path and state of the current target /// let path = watcher.get_path(index).unwrap(); /// let state = watcher.get_state(index).unwrap(); /// /// match transition { /// Transition::Created => { /* The watched file has been created */ }, /// Transition::Modified => { /* The watched file has been modified */ }, /// Transition::Deleted => { /* The watched file has been deleted */ }, /// Transition::None => { /* None of the above transitions were observed */ }, /// } /// } /// } /// ``` pub fn watch(&mut self) -> Vec<Transition> { let mut result = Vec::new(); for (index, target) in self.targets.iter().enumerate() { let previous_state = self.states.get(index).unwrap(); let current_state = compute_state(target); let mut transition = Transition::None; // Check for state transitions match (previous_state, ¤t_state) { // The file was created (WatchState::DoesNotExist, WatchState::Exists(_)) => { transition = Transition::Created; } // The file was deleted (WatchState::Exists(_), WatchState::DoesNotExist) => { transition = Transition::Deleted; } // The file was modified (WatchState::Exists(Some(t1)), WatchState::Exists(Some(t2))) if t1 != t2 => { transition = Transition::Modified; } _ => {} }; // now update our state vector *self.states.get_mut(index).unwrap() = current_state; result.push(transition); } result } } #[cfg(test)] mod tests { use crate::{BasicTarget, Transition, Watcher}; use std::io::{Error, Write}; use std::thread::sleep; use std::time::Duration; use tempfile::NamedTempFile; #[test] /// Creates a temporary file and tests the modification + deletion transitions fn transitions() -> Result<(), Error> { let mut watcher: Watcher<BasicTarget> = Watcher::new(); // Open a named temporary file & add it to our watcher let tmp = NamedTempFile::new()?; watcher.add_target(BasicTarget::new(tmp.path())); // We're going to modify our temporary file - to ensure the modification time // ono our temporary file changes, we wait a bit over a second before modifying sleep(Duration::from_millis(1500)); { let mut handle = tmp.reopen()?; write!(handle, "test")?; } // The watcher should notice the modification transition assert_eq!(watcher.watch(), vec![Transition::Modified]); // Delete the temporary file tmp.close()?; // The watcher should observe the deletion transition assert_eq!(watcher.watch(), vec![Transition::Deleted]); Ok(()) } }