indexedlog: add OpenOptions::index

Summary:
Make it a bit easier to define indexes.

Before:

    OpenOptions::new()
      .index_defs(vec![IndexDef::new("first-byte", |_| {
          vec![IndexOutput::Reference(0..1)]
      })])

After:

    OpenOptions::new()
      .index("first-byte", |_| vec![IndexOutput::Reference(0..1)])

Reviewed By: kulshrax

Differential Revision: D14690357

fbshipit-source-id: 6e80a91f4279f960d9f41369c228e79023b5164c

lib/indexedlog/src/log.rs

@@ -818,6 +818,15 @@ impl OpenOptions {
         }
     }
 
+    /// Add an index function.
+    ///
+    /// This is a convenient way to define indexes without using [`IndexDef`]
+    /// explictly.
+    pub fn index(mut self, name: &'static str, func: fn(&[u8]) -> Vec<IndexOutput>) -> Self {
+        self.index_defs.push(IndexDef::new(name, func));
+        self
+    }
+
     /// Sets index definitions.
     ///
     /// See [`IndexDef::new`] for details.
@@ -1409,14 +1418,16 @@ mod tests {
         let first_index =
             |_data: &[u8]| vec![IndexOutput::Reference(0..2), IndexOutput::Reference(3..5)];
         let second_index = |data: &[u8]| vec![IndexOutput::Owned(Box::from(&data[5..10]))];
-        let mut log = Log::open(
-            dir.path(),
-            vec![
+        let third_index = |_: &[u8]| vec![IndexOutput::Owned(Box::from(&b"x"[..]))];
+        let mut log = OpenOptions::new()
+            .create(true)
+            .index_defs(vec![
                 IndexDef::new("first", first_index).lag_threshold(0),
                 IndexDef::new("second", second_index).lag_threshold(0),
-            ],
-        )
-        .unwrap();
+            ])
+            .index("third", third_index)
+            .open(dir.path())
+            .unwrap();
 
         let mut expected_keys1 = vec![];
         let mut expected_keys2 = vec![];
@@ -1447,6 +1458,7 @@ mod tests {
         }
         assert_eq!(found_keys1, expected_keys1);
         assert_eq!(found_keys2, expected_keys2);
+        assert_eq!(log.iter().count(), log.lookup(2, b"x").unwrap().count());
     }
 
     quickcheck! {

lib/indexedlog/src/rotate.rs

@@ -86,6 +86,12 @@ impl OpenOptions {
         self
     }
 
+    /// Add an index function.
+    pub fn index(mut self, name: &'static str, func: fn(&[u8]) -> Vec<log::IndexOutput>) -> Self {
+        self.log_open_options = self.log_open_options.index(name, func);
+        self
+    }
+
     /// Set the index definitions.
     ///
     /// See [`IndexDef`] for details.
@@ -374,9 +380,7 @@ mod tests {
             .create(true)
             .max_bytes_per_log(100)
             .max_log_count(2)
-            .index_defs(vec![IndexDef::new("first-byte", |_| {
-                vec![IndexOutput::Reference(0..1)]
-            })])
+            .index("first-byte", |_| vec![IndexOutput::Reference(0..1)])
             .open(&dir)
             .unwrap();
 

lib/nodemap/src/nodemap.rs

@@ -4,7 +4,7 @@ use std::ops::Range;
 use std::path::Path;
 
 use failure::Fallible;
-use indexedlog::log::{IndexDef, IndexOutput, Log};
+use indexedlog::log::{self, IndexOutput, Log};
 use types::errors::KeyError;
 use types::node::Node;
 
@@ -32,13 +32,11 @@ impl NodeMap {
         let first_index = |_data: &[u8]| vec![IndexOutput::Reference(0..20)];
         let second_index = |_data: &[u8]| vec![IndexOutput::Reference(20..40)];
         Ok(NodeMap {
-            log: Log::open(
-                dir,
-                vec![
-                    IndexDef::new("first", first_index),
-                    IndexDef::new("second", second_index),
-                ],
-            )?,
+            log: log::OpenOptions::new()
+                .create(true)
+                .index("first", first_index)
+                .index("second", second_index)
+                .open(dir)?,
         })
     }