rdkafka 0.8.0

Rust wrapper for librdkafka
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
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

//! Common client functionalities.
use rdsys;
use rdsys::types::*;

use std::ffi::{CString, CStr};
use std::mem;
use std::os::raw::c_void;
use std::ptr;

use serde_json;

use config::{ClientConfig, NativeClientConfig, RDKafkaLogLevel};
use error::{IsError, KafkaError, KafkaResult};
use groups::GroupList;
use metadata::Metadata;
use statistics::Statistics;
use util::bytes_cstr_to_owned;

/// A Context is an object that can store user-defined data and on which callbacks can be
/// defined. Refer to the list of methods to see which callbacks can currently be overridden.
/// The context must be thread safe, and might be owned by multiple threads.
pub trait Context: Send + Sync {
    /// Receives log lines from librdkafka.
    fn log(&self, level: RDKafkaLogLevel, fac: &str, log_message: &str) {
        match level {
            RDKafkaLogLevel::Emerg => error!("librdkafka: {} {}", fac, log_message),
            RDKafkaLogLevel::Alert => error!("librdkafka: {} {}", fac, log_message),
            RDKafkaLogLevel::Critical => error!("librdkafka: {} {}", fac, log_message),
            RDKafkaLogLevel::Error => error!("librdkafka: {} {}", fac, log_message),
            RDKafkaLogLevel::Warning => warn!("librdkafka: {} {}", fac, log_message),
            RDKafkaLogLevel::Notice => info!("librdkafka: {} {}", fac, log_message),
            RDKafkaLogLevel::Info => info!("librdkafka: {} {}", fac, log_message),
            RDKafkaLogLevel::Debug => debug!("librdkafka: {} {}", fac, log_message),
        }
    }

    /// Receives the statistics of the librdkafka client. To enable, the
    /// "statistics.interval.ms" configuration parameter must be specified.
    fn stats(&self, statistics: Statistics) {
        info!("Client stats: {:?}", statistics);
    }

    // NOTE: when adding a new method, remember to add it to the FutureProducerContext as well.
    // https://github.com/rust-lang/rfcs/pull/1406 will maybe help in the future.
}

/// An empty context that can be used when no context is needed.
#[derive(Clone, Default)]
pub struct EmptyContext;

impl Context for EmptyContext { }

impl EmptyContext {
    pub fn new() -> EmptyContext {
        EmptyContext {}
    }
}

//
// ********** CLIENT **********
//

/// A native rdkafka-sys client. This struct shouldn't be used directly. Use higher level `Client`
/// or producers and consumers.
pub struct NativeClient {
    ptr: *mut RDKafka,
}

// The library is completely thread safe, according to the documentation.
unsafe impl Sync for NativeClient {}
unsafe impl Send for NativeClient {}

impl NativeClient {
    /// Wraps a pointer to an RDKafka object and returns a new NativeClient.
    pub fn from_ptr(ptr: *mut RDKafka) -> NativeClient {
        trace!("Create new NativeClient {:p}", ptr);
        NativeClient {ptr: ptr}
    }

    /// Returns the wrapped pointer to RDKafka.
    pub fn ptr(&self) -> *mut RDKafka {
        self.ptr
    }
}

impl Drop for NativeClient {
    fn drop(&mut self) {
        trace!("Destroy rd_kafka {:p}", self.ptr);
        unsafe {
            rdsys::rd_kafka_destroy(self.ptr);
            rdsys::rd_kafka_wait_destroyed(1000);
        }
    }
}

/// A low level rdkafka client. This client shouldn't be used directly. The producer and consumer modules
/// provide different producer and consumer implementations based on top of `Client` that can be
/// used instead.
pub struct Client<C: Context> {
    native: NativeClient,
    context: Box<C>,
}

impl<C: Context> Client<C> {
    /// Creates a new `Client` given a configuration, a client type and a context.
    pub fn new(config: &ClientConfig, native_config: NativeClientConfig, rd_kafka_type: RDKafkaType,
               context: C)
            -> KafkaResult<Client<C>> {
        let errstr = [0i8; 1024];
        let mut boxed_context = Box::new(context);
        unsafe { rdsys::rd_kafka_conf_set_opaque(
            native_config.ptr(), (&mut *boxed_context) as *mut C as *mut c_void) };
        unsafe { rdsys::rd_kafka_conf_set_log_cb(native_config.ptr(), Some(native_log_cb::<C>)) };
        unsafe { rdsys::rd_kafka_conf_set_stats_cb(native_config.ptr(), Some(native_stats_cb::<C>)) };

        let client_ptr = unsafe {
            rdsys::rd_kafka_new(rd_kafka_type, native_config.ptr_move(), errstr.as_ptr() as *mut i8, errstr.len())
        };

        if client_ptr.is_null() {
            let descr = unsafe { bytes_cstr_to_owned(&errstr) };
            return Err(KafkaError::ClientCreation(descr));
        }

        unsafe { rdsys::rd_kafka_set_log_level(client_ptr, config.log_level as i32) };

        Ok(Client {
            native: NativeClient::from_ptr(client_ptr),
            context: boxed_context,
        })
    }

    /// Returns a pointer to the native rdkafka-sys client.
    pub fn native_ptr(&self) -> *mut RDKafka {
        self.native.ptr
    }

    /// Returns a reference to the context.
    pub fn context(&self) -> &C {
        self.context.as_ref()
    }

    /// Returns the metadata information for all the topics in the cluster.
    pub fn fetch_metadata(&self, timeout_ms: i32) -> KafkaResult<Metadata> {
        let mut metadata_ptr: *const RDKafkaMetadata = ptr::null_mut();
        trace!("Starting metadata fetch");
        let ret = unsafe {
            rdsys::rd_kafka_metadata(
                self.native_ptr(),
                1,   // All topics
                ptr::null::<u8>() as *mut RDKafkaTopic,
                &mut metadata_ptr as *mut *const RDKafkaMetadata,
                timeout_ms)
        };
        trace!("Metadata fetch completed");
        if ret.is_error() {
            return Err(KafkaError::MetadataFetch(ret));
        }

        Ok(Metadata::from_ptr(metadata_ptr))
    }

    /// Returns high and low watermark for the specified topic and partition.
    pub fn fetch_watermarks(&self, topic: &str, partition: i32, timeout_ms: i32) -> KafkaResult<(i64, i64)> {
        let mut low = -1;
        let mut high = -1;
        let topic_c = CString::new(topic.to_string())?;
        let ret = unsafe {
            rdsys::rd_kafka_query_watermark_offsets(self.native_ptr(), topic_c.as_ptr(), partition,
                                                    &mut low as *mut i64, &mut high as *mut i64, timeout_ms)
        };
        if ret.is_error() {
            return Err(KafkaError::MetadataFetch(ret));
        }
        Ok((low, high))
    }

    /// Returns the group membership information for the given group. If no group is
    /// specified, all groups will be returned.
    pub fn fetch_group_list(&self, group: Option<&str>, timeout_ms: i32) -> KafkaResult<GroupList> {
        // Careful with group_c getting freed before time
        let group_c = CString::new(group.map_or("".to_string(), |g| g.to_string()))?;
        let group_c_ptr = if group.is_some() {
            group_c.as_ptr()
        } else {
            ptr::null_mut()
        };
        let mut group_list_ptr: *const RDKafkaGroupList = ptr::null_mut();
        trace!("Starting group list fetch");
        let ret = unsafe {
            rdsys::rd_kafka_list_groups(
                self.native_ptr(),
                group_c_ptr,
                &mut group_list_ptr as *mut *const RDKafkaGroupList,
                timeout_ms)
        };
        trace!("Group list fetch completed");
        if ret.is_error() {
            return Err(KafkaError::GroupListFetch(ret));
        }

        Ok(GroupList::from_ptr(group_list_ptr))
    }
}

pub unsafe extern "C" fn native_log_cb<C: Context>(
        client: *const RDKafka, level: i32,
        fac: *const i8, buf: *const i8) {
    let fac = CStr::from_ptr(fac).to_string_lossy();
    let log_message = CStr::from_ptr(buf).to_string_lossy();

    let context = Box::from_raw(rdsys::rd_kafka_opaque(client) as *mut C);
    (*context).log(RDKafkaLogLevel::from_int(level), fac.trim(), log_message.trim());
    mem::forget(context);   // Do not free the context
}

pub unsafe extern "C" fn native_stats_cb<C: Context>(
        _conf: *mut RDKafka, json: *mut i8, json_len: usize,
        opaque: *mut c_void) -> i32 {
    let context = Box::from_raw(opaque as *mut C);

    let statistics_json = String::from_raw_parts(json as *mut u8, json_len, json_len);
    match serde_json::from_str(&statistics_json) {
        Ok(stats) => (*context).stats(stats),
        Err(e) => error!("Could not parse statistics json: {}", e)
    }

    mem::forget(context);   // Do not free the context

    1 // librdkafka will not free the json buffer
}

#[cfg(test)]
mod tests {
    // Just call everything to test there no panics by default, behavior
    // is tested in the integrations tests.

    extern crate rdkafka_sys as rdsys;
    use rdsys::types::*;
    use config::ClientConfig;
    use super::*;

    #[test]
    fn test_client() {
        let config = ClientConfig::new();
        let native_config = config.create_native_config().unwrap();
        let client = Client::new(&config, native_config, RDKafkaType::RD_KAFKA_PRODUCER,
                                 EmptyContext::new()).unwrap();
        assert!(!client.native_ptr().is_null());
    }
}