log4j 0.1.0

Library to log to Java's log4j from Rust
Documentation 
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

use crate::error::Result;
use jni::objects::{JMethodID, JObject, JValue};
use jni::signature::{JavaType, Primitive};
use jni::JNIEnv;
use std::sync::{Arc, Mutex};

const LOG_MANAGER_CLASS: &str = "org/apache/log4j/LogManager";
const CATEGORY_CLASS: &str = "org/apache/log4j/Category";

struct InnerLogger<'a> {
    env:            &'a JNIEnv<'a>,
    logger:         JObject<'a>,         // This is an instance of org.apache.log4j.Logger
    info_method:    JMethodID<'a>,  // Logger#info(Object)
    error_method:   JMethodID<'a>, // Logger#error(Object)
    warn_method:    JMethodID<'a>,  // Logger#warn(Object)
    debug_method:   JMethodID<'a>, // Logger#debug(Object)
}

/// The JavaLogger
pub struct JavaLogger<'a> {
    inner: Arc<Mutex<InnerLogger<'a>>>,
}

// Required because the compiler does not pick up that JavaLogger can be Send+Sync
// InnerLogger is !Send + !Sync, but we're wrapping it in an Arc<Mutex<T>>
unsafe impl<'a> Send for JavaLogger<'a> {}
unsafe impl<'a> Sync for JavaLogger<'a> {}

/// The log level to output to
pub enum LogLevel {
    /// ERROR level
    Error,
    /// WARN level
    Warn,
    /// INFO level
    Info,
    /// DEBUG level, also applicable to TRACE logging
    Debug,
}

impl<'a> JavaLogger<'a> {
    /// Create a new logger
    ///
    /// # Params
    /// - `class_name` The name of Class which should be used by log4j on the Java side
    ///
    /// # Error
    /// - If one of the underlying JNI calls fail
    pub fn new<S: AsRef<str>>(env: &'a JNIEnv<'a>, class_name: S) -> Result<Self> {
        let log_manager_class = env.find_class(LOG_MANAGER_CLASS)?;
        let logger_value = env.call_static_method(log_manager_class,             "getLogger","(Ljava/lang/String;)Lorg/apache/log4j/Logger;",&[Self::jstring(env, class_name.as_ref())?])?;
        let logger = logger_value.l()?;

        let category_class = env.find_class(CATEGORY_CLASS)?;
        let info_method = env.get_method_id(category_class, "info", "(Ljava/lang/Object;)V")?;
        let error_method = env.get_method_id(category_class, "error", "(Ljava/lang/Object;)V")?;
        let warn_method = env.get_method_id(category_class, "warn", "(Ljava/lang/Object;)V")?;
        let debug_method = env.get_method_id(category_class, "debug", "(Ljava/lang/Object;)V")?;

        Ok(Self {
            inner: Arc::new(Mutex::new(InnerLogger {
                env,
                logger,
                info_method,
                error_method,
                warn_method,
                debug_method,
            })),
        })
    }

    /// Log to log4j
    ///
    /// # Error
    /// - If one of the underlying JNI calls fail
    pub fn log<S: AsRef<str>>(&self, level: LogLevel, content: S) -> Result<()> {
        let logger = self.inner.lock().expect("Failed to lock inner logger");
        match level {
            LogLevel::Error => Self::log_error(&logger, content.as_ref())?,
            LogLevel::Warn => Self::log_warn(&logger, content.as_ref())?,
            LogLevel::Info => Self::log_info(&logger, content.as_ref())?,
            LogLevel::Debug => Self::log_debug(&logger, content.as_ref())?,
        };

        Ok(())
    }

    /// Log to the ERROR level
    ///
    /// # Error
    /// - If one of the underlying JNI calls fail
    fn log_error<'b>(logger: &'b InnerLogger<'a>, msg: &str) -> Result<()>
    where
        'a: 'b,
    {
        logger.env.call_method_unchecked(logger.logger,logger.error_method,JavaType::Primitive(Primitive::Void), &[Self::jstring(logger.env, msg)?])?;
        Ok(())
    }

    /// Log to the WARN level
    ///
    /// # Error
    /// - If one of the underlying JNI calls fail
    fn log_warn<'b>(logger: &'b InnerLogger<'a>, msg: &str) -> Result<()>
    where
        'a: 'b,
    {
        logger.env.call_method_unchecked(logger.logger,logger.warn_method,JavaType::Primitive(Primitive::Void),&[Self::jstring(logger.env, msg)?])?;
        Ok(())
    }

    /// Log to the INFO level
    ///
    /// # Error
    /// - If one of the underlying JNI calls fail
    fn log_info<'b>(logger: &'b InnerLogger<'a>, msg: &str) -> Result<()>
    where
        'a: 'b,
    {
        logger.env.call_method_unchecked(logger.logger,logger.info_method,JavaType::Primitive(Primitive::Void),&[Self::jstring(logger.env, msg)?])?;
        Ok(())
    }

    /// Log to the DEBUG level
    ///
    /// # Error
    /// - If one of the underlying JNI calls fail
    fn log_debug<'b>(logger: &'b InnerLogger<'a>, msg: &str) -> Result<()>
    where
        'a: 'b,
    {
        logger.env.call_method_unchecked(logger.logger,logger.debug_method,JavaType::Primitive(Primitive::Void),&[Self::jstring(logger.env, msg)?])?;
        Ok(())
    }

    /// Turn a string into a JValue containing a JString
    ///
    /// # Error
    /// - If one of the underlying JNI calls fail
    fn jstring(env: &'a JNIEnv<'a>, content: &str) -> Result<JValue<'a>> {
        let str = env.new_string(content)?;
        Ok(JValue::Object(str.into()))
    }
}

#[cfg(test)]
mod test {
    use super::*;
    use crate::test::JVM;

    fn setup_log4j(logger: &JavaLogger) -> Result<()> {
        let logger = logger.inner.lock().unwrap();
        let env = logger.env;

        let pattern_layout_class = env.find_class("org/apache/log4j/PatternLayout")?;
        let pattern_layout = env.new_object(pattern_layout_class,"(Ljava/lang/String;)V",&[JValue::Object(env.new_string("%r [%t] %p %c %x - %m%n")?.into())])?;

        let console_appender_class = env.find_class("org/apache/log4j/ConsoleAppender")?;
        let console_appender = env.new_object(console_appender_class,"(Lorg/apache/log4j/Layout;)V",&[JValue::Object(pattern_layout)])?;

        let category_class = env.find_class(CATEGORY_CLASS)?;
        let add_apender_method = env.get_method_id(category_class,"addAppender","(Lorg/apache/log4j/Appender;)V")?;
        env.call_method_unchecked(logger.logger,add_apender_method,JavaType::Primitive(Primitive::Void),&[JValue::Object(console_appender)])?;
        Ok(())
    }

    #[test]
    fn info() {
        let jvm = JVM.lock().expect("Failed to lock JVM");
        let env = jvm.attach_current_thread().expect("Failed to attach current thread to the JVM");
        let logger = JavaLogger::new(&env, "com.example.Info").expect("Failed to create JavaLogger");
        setup_log4j(&logger).expect("Failed to set up log4j");

        let inner_logger = logger.inner.lock().expect("Failed to lock inner logger");
        JavaLogger::log_info(&inner_logger, "Info log!").expect("Failed to log to INFO");
    }

    #[test]
    fn warn() {
        let jvm = JVM.lock().expect("Failed to lock JVM");
        let env = jvm.attach_current_thread().expect("Failed to attach current thread to the JVM");
        let logger = JavaLogger::new(&env, "com.example.Warn").expect("Failed to create JavaLogger");
        setup_log4j(&logger).expect("Failed to set up log4j");

        let inner_logger = logger.inner.lock().expect("Failed to lock inner logger");
        JavaLogger::log_warn(&inner_logger, "Warning log!").expect("Failed to log to WARN");
    }

    #[test]
    fn error() {
        let jvm = JVM.lock().expect("Failed to lock JVM");
        let env = jvm.attach_current_thread().expect("Failed to attach current thread to the JVM");
        let logger = JavaLogger::new(&env, "com.example.Error").expect("Failed to create JavaLogger");
        setup_log4j(&logger).expect("Failed to set up log4j");

        let inner_logger = logger.inner.lock().expect("Failed to lock inner logger");
        JavaLogger::log_error(&inner_logger, "Error log!").expect("Failed to log to ERROR");
    }

    #[test]
    fn trace_and_debug() {
        let jvm = JVM.lock().expect("Failed to lock JVM");
        let env = jvm.attach_current_thread().expect("Failed to attach current thread to the JVM");
        let logger = JavaLogger::new(&env, "com.example.Debug").expect("Failed to create JavaLogger");
        setup_log4j(&logger).expect("Failed to set up log4j");

        let inner_logger = logger.inner.lock().expect("Failed to lock inner logger");
        JavaLogger::log_debug(&inner_logger, "Trace and debug log!").expect("Failed to log to DEBUG");
    }

    #[test]
    fn log_general() {
        let jvm = JVM.lock().expect("Failed to lock JVM");
        let env = jvm.attach_current_thread().expect("Failed to attach current thread to the JVM");
        let logger = JavaLogger::new(&env, "com.example.General").expect("Failed to create JavaLogger");
        setup_log4j(&logger).expect("Failed to set up log4j");

        logger.log(LogLevel::Error, "Error!").expect("Failed to log to ERROR level");
        logger.log(LogLevel::Warn, "Warn!").expect("Failed to log to WARN level");
        logger.log(LogLevel::Info, "Info!").expect("Failed to log to INFO level");
        logger.log(LogLevel::Debug, "Debug!").expect("Failed to log to DEBUG level");
    }
}