zova 0.21.0

Safe Rust bindings for Zova, a SQLite-backed embedded database for records, objects, vectors, and graph relationships.
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

use crate::database::{cstring, db_status, DatabaseInner};
use crate::error::{Error, Result};
use std::marker::PhantomData;
use std::ptr::{self, NonNull};
use std::rc::Rc;

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Notification {
    pub channel: String,
    pub payload: String,
    pub sequence: u64,
    pub dropped_before: u64,
}

pub struct Subscription {
    raw: Option<NonNull<zova_sys::zova_subscription>>,
    db: *mut zova_sys::zova_database,
    _database: Rc<DatabaseInner>,
    _not_send_sync: PhantomData<Rc<()>>,
}

impl Subscription {
    pub(crate) fn new(
        raw: NonNull<zova_sys::zova_subscription>,
        database: Rc<DatabaseInner>,
    ) -> Self {
        let db = database.raw_ptr();
        Self {
            raw: Some(raw),
            db,
            _database: database,
            _not_send_sync: PhantomData,
        }
    }

    pub fn try_receive(&mut self) -> Result<Option<Notification>> {
        let raw = self
            .raw
            .ok_or_else(|| Error::from_status(zova_sys::ZOVA_MISUSE, None))?;
        let mut notification = empty_notification();
        let mut has_notification = 0;
        let request = zova_sys::zova_subscription_try_receive_request {
            subscription: raw.as_ptr(),
            out_notification: &mut notification,
            out_has_notification: &mut has_notification,
        };
        db_status(self.db, unsafe {
            zova_sys::zova_subscription_try_receive(&request)
        })?;
        if has_notification == 0 {
            return Ok(None);
        }
        Ok(Some(take_notification(&mut notification)?))
    }

    pub fn close(&mut self) -> Result<()> {
        if let Some(raw) = self.raw {
            db_status(self.db, unsafe {
                zova_sys::zova_subscription_close(raw.as_ptr())
            })?;
            self.raw = None;
        }
        Ok(())
    }
}

impl Drop for Subscription {
    fn drop(&mut self) {
        if let Some(raw) = self.raw.take() {
            unsafe {
                let _ = zova_sys::zova_subscription_close(raw.as_ptr());
            }
        }
    }
}

pub(crate) fn empty_notification() -> zova_sys::zova_notification {
    zova_sys::zova_notification {
        channel: ptr::null_mut(),
        channel_len: 0,
        payload: ptr::null_mut(),
        payload_len: 0,
        sequence: 0,
        dropped_before: 0,
    }
}

pub(crate) fn take_notification(
    notification: &mut zova_sys::zova_notification,
) -> Result<Notification> {
    let channel = string_from_parts(notification.channel, notification.channel_len)?;
    let payload = string_from_parts(notification.payload, notification.payload_len)?;
    let out = Notification {
        channel,
        payload,
        sequence: notification.sequence,
        dropped_before: notification.dropped_before,
    };
    unsafe {
        zova_sys::zova_notification_free(notification);
    }
    Ok(out)
}

pub(crate) fn listen_raw(
    db: *mut zova_sys::zova_database,
    channel: &str,
) -> Result<NonNull<zova_sys::zova_subscription>> {
    let channel = cstring(channel, "notification channel")?;
    let mut subscription = ptr::null_mut();
    let request = zova_sys::zova_database_listen_request {
        db,
        channel: channel.as_ptr(),
        out_subscription: &mut subscription,
    };
    db_status(db, unsafe { zova_sys::zova_database_listen(&request) })?;
    NonNull::new(subscription).ok_or_else(|| Error::from_status(zova_sys::ZOVA_MISUSE, None))
}

pub(crate) fn notify_raw(
    db: *mut zova_sys::zova_database,
    channel: &str,
    payload: &str,
) -> Result<()> {
    let channel = cstring(channel, "notification channel")?;
    let request = zova_sys::zova_database_notify_request {
        db,
        channel: channel.as_ptr(),
        payload: payload.as_bytes().as_ptr(),
        payload_len: payload.len(),
    };
    db_status(db, unsafe { zova_sys::zova_database_notify(&request) })
}

fn string_from_parts(ptr: *mut std::os::raw::c_char, len: usize) -> Result<String> {
    if ptr.is_null() {
        return Ok(String::new());
    }
    let bytes = unsafe { std::slice::from_raw_parts(ptr.cast::<u8>(), len) };
    String::from_utf8(bytes.to_vec()).map_err(|_| Error::InvalidUtf8Text)
}