Add test and doc

Besides, fix some small problem:

1. Typo and format cases in README.md.
2. compile error in `rust/build.rs`.

Author: Lostlitus

README.md

@@ -9,9 +9,11 @@
 `hdfs-native` is an HDFS client written natively in Rust. It supports nearly all major features of an HDFS client, and several key client configuration options listed below.
 
 ## Supported HDFS features
+
 Here is a list of currently supported and unsupported but possible future features.
 
 ### HDFS Operations
+
 - [x] Listing
 - [x] Reading
 - [x] Writing
@@ -24,14 +26,16 @@ Here is a list of currently supported and unsupported but possible future featur
 - [x] Set timestamps
 
 ### HDFS Features
+
 - [x] Name Services
 - [x] Observer reads
 - [x] ViewFS
 - [x] Router based federation
 - [x] Erasure coded reads and writes
-    - RS schema only, no support for RS-Legacy or XOR
+  - RS schema only, no support for RS-Legacy or XOR
 
 ### Security Features
+
 - [x] Kerberos authentication (GSSAPI SASL support) (requires libgssapi_krb5, see below)
 - [x] Token authentication (DIGEST-MD5 SASL support)
 - [x] NameNode SASL connection
@@ -40,47 +44,54 @@ Here is a list of currently supported and unsupported but possible future featur
 - [ ] Encryption at rest (KMS support)
 
 ### Kerberos Support
+
 Kerberos (SASL GSSAPI) mechanism is supported through a runtime dynamic link to `libgssapi_krb5`. This must be installed separately, but is likely already installed on your system. If not you can install it by:
 
 #### Debian-based systems
+
 ```bash
 apt-get install libgssapi-krb5-2
 ```
 
 #### RHEL-based systems
+
 ```bash
 yum install krb5-libs
 ```
 
 #### MacOS
+
 ```bash
 brew install krb5
 ```
 
 #### Windows
+
 Download and install the Microsoft Kerberos package from https://web.mit.edu/kerberos/dist/
 
 Copy the `<INSTALL FOLDER>\MIT\Kerberos\bin\gssapi64.dll` file to a folder in %PATH% and change the name to `gssapi_krb5.dll`
 
 ## Supported HDFS Settings
-The client will attempt to read Hadoop configs `core-site.xml` and `hdfs-site.xml` in the directories `$HADOOP_CONF_DIR` or if that doesn't exist, `$HADOOP_HOME/etc/hadoop`. Currently the supported configs that are used are:
+
+The client will attempt to read Hadoop configs `core-site.xml` and `hdfs-site.xml` in the directories `$HADOOP_CONF_DIR` or if that doesn't exist, `$HADOOP_HOME/etc/hadoop`. Passing configs in run time is supported as well via `client::ClientBuilder`. Currently the supported configs that are used are:
+
 - `fs.defaultFS` - Client::default() support
 - `dfs.ha.namenodes` - name service support
 - `dfs.namenode.rpc-address.*` - name service support
 - `dfs.client.failover.resolve-needed.*` - DNS based NameNode discovery
 - `dfs.client.failover.resolver.useFQDN.*` - DNS based NameNode discovery
 - `dfs.client.failover.random.order.*` - Randomize order of NameNodes to try
 - `dfs.client.failover.proxy.provider.*` - Supports the behavior of the following proxy providers. Any other values will default back to the `ConfiguredFailoverProxyProvider` behavior:
-    - `org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider`
-    - `org.apache.hadoop.hdfs.server.namenode.ha.ObserverReadProxyProvider`
-    - `org.apache.hadoop.hdfs.server.namenode.ha.RouterObserverReadConfiguredFailoverProxyProvider`
+  - `org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider`
+  - `org.apache.hadoop.hdfs.server.namenode.ha.ObserverReadProxyProvider`
+  - `org.apache.hadoop.hdfs.server.namenode.ha.RouterObserverReadConfiguredFailoverProxyProvider`
 - `dfs.client.block.write.replace-datanode-on-failure.enable`
 - `dfs.client.block.write.replace-datanode-on-failure.policy`
 - `dfs.client.block.write.replace-datanode-on-failure.best-effort`
 - `fs.viewfs.mounttable.*.link.*` - ViewFS links
 - `fs.viewfs.mounttable.*.linkFallback` - ViewFS link fallback
 
-All other settings are generally assumed to be the defaults currently. For instance, security is assumed to be enabled and SASL negotiation is always done, but on insecure clusters this will just do SIMPLE authentication. Any setups that require other customized Hadoop client configs may not work correctly. 
+All other settings are generally assumed to be the defaults currently. For instance, security is assumed to be enabled and SASL negotiation is always done, but on insecure clusters this will just do SIMPLE authentication. Any setups that require other customized Hadoop client configs may not work correctly.
 
 ## Building
 
@@ -89,19 +100,23 @@ cargo build
 ```
 
 ## Object store implementation
+
 An object_store implementation for HDFS is provided in the [hdfs-native-object-store](https://github.com/datafusion-contrib/hdfs-native-object-store) crate.
 
 ## Running tests
+
 The tests are mostly integration tests that utilize a small Java application in `rust/mindifs/` that runs a custom `MiniDFSCluster`. To run the tests, you need to have Java, Maven, Hadoop binaries, and Kerberos tools available and on your path. Any Java version between 8 and 17 should work.
 
 ```bash
-cargo test -p hdfs-native --features intergation-test
+cargo test -p hdfs-native --features integration-test
 ```
 
 ### Python tests
+
 See the [Python README](./python/README.md)
 
 ## Running benchmarks
+
 Some of the benchmarks compare performance to the JVM based client through libhdfs via the fs-hdfs3 crate. Because of that, some extra setup is required to run the benchmarks:
 
 ```bash
@@ -110,13 +125,15 @@ export CLASSPATH=$(hadoop classpath)
 ```
 
 then you can run the benchmarks with
+
 ```bash
 cargo bench -p hdfs-native --features benchmark
 ```
 
 The `benchmark` feature is required to expose `minidfs` and the internal erasure coding functions to benchmark.
 
 ## Running examples
+
 The examples make use of the `minidfs` module to create a simple HDFS cluster to run the example. This requires including the `integration-test` feature to enable the `minidfs` module. Alternatively, if you want to run the example against an existing HDFS cluster you can exclude the `integration-test` feature and make sure your `HADOOP_CONF_DIR` points to a directory with HDFS configs for talking to your cluster.
 
 ```bash

rust/build.rs

@@ -3,7 +3,9 @@ use std::io::Result;
 fn main() -> Result<()> {
     #[cfg(feature = "generate-protobuf")]
     {
-        std::env::set_var("PROTOC", protobuf_src::protoc());
+        unsafe {
+            std::env::set_var("PROTOC", protobuf_src::protoc());
+        }
 
         prost_build::compile_protos(
             &[

rust/src/client.rs

@@ -190,16 +190,41 @@ impl IORuntime {
     }
 }
 
-/// Builds a new [Client] instance. By default, configs will be loaded from the default config directories with the following precedence:
+/// Builds a new [Client] instance. Configs will be loaded with the following precedence:
+///
+/// - If method `ClientBuilder::with_config_dir` is invoked, configs will be loaded from `${config_dir}/{core,hdfs}-site.xml`
 /// - If the `HADOOP_CONF_DIR` environment variable is defined, configs will be loaded from `${HADOOP_CONF_DIR}/{core,hdfs}-site.xml`
 /// - If the `HADOOP_HOME` environment variable is defined, configs will be loaded from `${HADOOP_HOME}/etc/hadoop/{core,hdfs}-site.xml`
-/// - Otherwise no default configs are defined
+/// - Otherwise no configs are defined
+///
+/// Finally, configs set by `with_config` will override the configs loaded above.
 ///
 /// If no URL is defined, the `fs.defaultFS` config must be defined and is used as the URL.
 ///
 /// # Examples
 ///
+/// Create a new client with given config directory
+///
+/// ```rust,no_run
+/// # use hdfs_native::ClientBuilder;
+/// let client = ClientBuilder::new()
+///     .with_config_dir("/opt/hadoop/etc/hadoop")
+///     .build()
+///     .unwrap();
+/// ```
+///
+/// Create a new client with the environment variable
+///
+/// ```rust,no_run
+/// # use hdfs_native::ClientBuilder;
+/// unsafe { std::env::set_var("HADOOP_CONF_DIR", "/opt/hadoop/etc/hadoop") };
+/// let client = ClientBuilder::new()
+///     .build()
+///     .unwrap();
+/// ```
+///
 /// Create a new client using the fs.defaultFS config
+///
 /// ```rust
 /// # use hdfs_native::ClientBuilder;
 /// let client = ClientBuilder::new()
@@ -209,6 +234,7 @@ impl IORuntime {
 /// ```
 ///
 /// Create a new client connecting to a specific URL:
+///
 /// ```rust
 /// # use hdfs_native::ClientBuilder;
 /// let client = ClientBuilder::new()
@@ -218,6 +244,7 @@ impl IORuntime {
 /// ```
 ///
 /// Create a new client using a dedicated tokio runtime for spawned tasks and IO operations
+///
 /// ```rust
 /// # use hdfs_native::ClientBuilder;
 /// let client = ClientBuilder::new()
@@ -1319,4 +1346,23 @@ mod test {
                 .is_ok()
         );
     }
+
+    #[test]
+    fn test_set_conf_dir() {
+        // Configuration directory set in run time overriding env one
+        // Case 1: conf dir not exists, build fail
+        assert!(
+            ClientBuilder::new()
+                .with_config_dir("target/test/non-exist-dir")
+                .build()
+                .is_err()
+        );
+        // Case 2: conf dir exists, build success
+        assert!(
+            ClientBuilder::new()
+                .with_config_dir("target/test")
+                .build()
+                .is_ok()
+        )
+    }
 }

rust/src/common/config.rs

@@ -43,23 +43,21 @@ pub struct Configuration {
 }
 
 impl Configuration {
-    pub fn new(
+    pub(crate) fn new(
         conf_dir: Option<String>,
         conf_map: Option<HashMap<String, String>>,
     ) -> Result<Self> {
-        let mut configration = Configuration {
-            map: HashMap::new(),
-        };
+        let mut map = HashMap::new();
 
         if let Some(conf_dir) = Self::parse_conf_dir(conf_dir) {
-            configration.map = Self::parse_conf(conf_dir)?;
+            map = Self::parse_conf(conf_dir)?;
         }
 
         if let Some(conf_map) = conf_map {
-            configration.map.extend(conf_map);
+            map.extend(conf_map);
         }
 
-        Ok(configration)
+        Ok(Configuration { map })
     }
 
     /// Get a value from the config, returning None if the key wasn't defined.