use random byte array instead of process_id and machine_id (#114)

* support wasm targets

* generate a 5-byte random array instead of machine-id + process-id

* remove wasm check from travis to pass decimal128 check in upstream master

Author: lrlna

Cargo.toml

@@ -29,7 +29,6 @@ serde = "1.0"
 serde_json = { version = "1.0", features = ["preserve_order"] }
 time = "0.1"
 linked-hash-map = "0.5"
-hostname = "0.1"
 hex = "0.3"
 md5 = "0.3"
 try_from = "0.2"

src/lib.rs

@@ -45,8 +45,6 @@
 extern crate byteorder;
 extern crate chrono;
 extern crate hex;
-extern crate hostname;
-extern crate libc;
 extern crate linked_hash_map;
 extern crate rand;
 extern crate serde;

src/oid.rs

@@ -1,34 +1,27 @@
 //! ObjectId
 
-use libc;
-
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::{error, fmt, io, result};
 
-use byteorder::{BigEndian, ByteOrder, LittleEndian};
-use md5;
+use byteorder::{BigEndian, ByteOrder};
 
 use hex::{self, FromHexError};
 
 use rand::{thread_rng, Rng};
 
-use hostname::get_hostname;
 use time;
 
 const TIMESTAMP_SIZE: usize = 4;
-const MACHINE_ID_SIZE: usize = 3;
-const PROCESS_ID_SIZE: usize = 2;
+const PROCESS_ID_SIZE: usize = 5;
 const COUNTER_SIZE: usize = 3;
 
 const TIMESTAMP_OFFSET: usize = 0;
-const MACHINE_ID_OFFSET: usize = TIMESTAMP_OFFSET + TIMESTAMP_SIZE;
-const PROCESS_ID_OFFSET: usize = MACHINE_ID_OFFSET + MACHINE_ID_SIZE;
+const PROCESS_ID_OFFSET: usize = TIMESTAMP_OFFSET + TIMESTAMP_SIZE;
 const COUNTER_OFFSET: usize = PROCESS_ID_OFFSET + PROCESS_ID_SIZE;
 
 const MAX_U24: usize = 0xFF_FFFF;
 
 static OID_COUNTER: AtomicUsize = AtomicUsize::new(0);
-static mut MACHINE_BYTES: Option<[u8; 3]> = None;
 
 /// Errors that can occur during OID construction and generation.
 #[derive(Debug)]
@@ -97,17 +90,13 @@ impl ObjectId {
     /// for more information.
     pub fn new() -> Result<ObjectId> {
         let timestamp = ObjectId::gen_timestamp();
-        let machine_id = ObjectId::gen_machine_id()?;
         let process_id = ObjectId::gen_process_id();
         let counter = ObjectId::gen_count()?;
 
         let mut buf: [u8; 12] = [0; 12];
         for i in 0..TIMESTAMP_SIZE {
             buf[TIMESTAMP_OFFSET + i] = timestamp[i];
         }
-        for i in 0..MACHINE_ID_SIZE {
-            buf[MACHINE_ID_OFFSET + i] = machine_id[i];
-        }
         for i in 0..PROCESS_ID_SIZE {
             buf[PROCESS_ID_OFFSET + i] = process_id[i];
         }
@@ -154,20 +143,6 @@ impl ObjectId {
         BigEndian::read_u32(&self.id)
     }
 
-    /// Retrieves the machine id associated with an ObjectId.
-    pub fn machine_id(&self) -> u32 {
-        let mut buf: [u8; 4] = [0; 4];
-        for i in 0..MACHINE_ID_SIZE {
-            buf[i] = self.id[MACHINE_ID_OFFSET + i];
-        }
-        LittleEndian::read_u32(&buf)
-    }
-
-    /// Retrieves the process id associated with an ObjectId.
-    pub fn process_id(&self) -> u16 {
-        LittleEndian::read_u16(&self.id[PROCESS_ID_OFFSET..])
-    }
-
     /// Retrieves the increment counter from an ObjectId.
     pub fn counter(&self) -> u32 {
         let mut buf: [u8; 4] = [0; 4];
@@ -193,47 +168,11 @@ impl ObjectId {
         buf
     }
 
-    // Generates a new machine id represented as an MD5-hashed 3-byte-encoded hostname string.
-    // Represented in Little Endian.
-    fn gen_machine_id() -> Result<[u8; 3]> {
-        // Short-circuit if machine id has already been calculated.
-        // Since the generated machine id is not variable, arising race conditions
-        // will have the same MACHINE_BYTES result.
-        unsafe {
-            if let Some(bytes) = MACHINE_BYTES.as_ref() {
-                return Ok(*bytes);
-            }
-        }
-
-        let hostname = get_hostname();
-        if hostname.is_none() {
-            return Err(Error::HostnameError);
-        }
-
-        // Hash hostname string
-        let digest = md5::compute(hostname.unwrap().as_str());
-        let hash = format!("{:x}", digest);
-
-        // Re-convert string to bytes and grab first three
-        let mut bytes = hash.bytes();
-        let mut vec: [u8; 3] = [0; 3];
-        for v in &mut vec {
-            match bytes.next() {
-                Some(b) => *v = b,
-                None => break,
-            }
-        }
-
-        unsafe { MACHINE_BYTES = Some(vec) };
-        Ok(vec)
-    }
-
-    // Gets the process ID and returns it as a 2-byte array.
-    // Represented in Little Endian.
-    fn gen_process_id() -> [u8; 2] {
-        let pid = unsafe { libc::getpid() as u16 };
-        let mut buf: [u8; 2] = [0; 2];
-        LittleEndian::write_u16(&mut buf, pid);
+    // Generate a random 5-byte array.
+    fn gen_process_id() -> [u8; 5] {
+        let rng = thread_rng().gen_range(0, MAX_U24) as u32;
+        let mut buf: [u8; 5] = [0; 5];
+        BigEndian::write_u32(&mut buf, rng);
         buf
     }
 
@@ -276,13 +215,6 @@ impl fmt::Debug for ObjectId {
     }
 }
 
-#[test]
-fn pid_generation() {
-    let pid = unsafe { libc::getpid() as u16 };
-    let generated = ObjectId::gen_process_id();
-    assert_eq!(pid, LittleEndian::read_u16(&generated));
-}
-
 #[test]
 fn count_generated_is_big_endian() {
     let start = 1_122_866;

tests/modules/oid.rs

@@ -3,23 +3,12 @@ use hex;
 
 #[test]
 fn deserialize() {
-    let bytes: [u8; 12] = [0xDEu8,
-                           0xADu8,
-                           0xBEu8,
-                           0xEFu8, // timestamp is 3735928559
-                           0xEFu8,
-                           0xCDu8,
-                           0xABu8, // machine_id is 11259375
-                           0xFAu8,
-                           0x29u8, // process_id is 10746
-                           0x11u8,
-                           0x22u8,
+    let bytes: [u8; 12] = [0xDEu8, 0xADu8, 0xBEu8, 0xEFu8, // timestamp is 3735928559
+                           0xEFu8, 0xCDu8, 0xABu8, 0xFAu8, 0x29u8, 0x11u8, 0x22u8,
                            0x33u8 /* increment is 1122867 */];
 
     let oid = ObjectId::with_bytes(bytes);
     assert_eq!(3735928559 as u32, oid.timestamp());
-    assert_eq!(11259375 as u32, oid.machine_id());
-    assert_eq!(10746 as u16, oid.process_id());
     assert_eq!(1122867 as u32, oid.counter());
 }
 
@@ -83,14 +72,15 @@ fn oid_not_equals() {
     assert!(oid1 != oid2);
 }
 
+// check that the last byte in objectIDs is increasing
 #[test]
-fn increasing() {
+fn counter_increasing() {
     let oid1_res = ObjectId::new();
     let oid2_res = ObjectId::new();
     assert!(oid1_res.is_ok());
     assert!(oid2_res.is_ok());
 
-    let oid1 = oid1_res.unwrap();
-    let oid2 = oid2_res.unwrap();
-    assert!(oid1 < oid2);
+    let oid1_bytes = oid1_res.unwrap().bytes();
+    let oid2_bytes = oid2_res.unwrap().bytes();
+    assert!(oid1_bytes[11] < oid2_bytes[11]);
 }