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
use_prelude!();
use ::ffi_sdk::{self, c_cb_params, COrderByParam, LiveQueryAvailability};
pub use event::LiveQueryEvent;
pub use single_document_event::SingleDocumentLiveQueryEvent;

use crate::{
    error::{DittoError, ErrorKind},
    subscription::Subscription,
};
mod event;
mod single_document_event;

pub use move_module::LiveQueryMove;
#[path = "move.rs"]
mod move_module;

trait_alias! {
    /// A closure which is called on each event for a single document live query
    /// (`find_by_id(...).observe(...)`)
    pub
    trait SingleDocumentEventHandler =
        FnMut(Option<BoxedDocument>, SingleDocumentLiveQueryEvent)
        + Send // can be dropped in another thread
        + 'static // cannot dangle
}

trait_alias! {
    /// A closure which is called on each event
    pub
    trait EventHandler =
        FnMut(Vec<BoxedDocument>, LiveQueryEvent)
        + Send // can be dropped in another thread
        + 'static // cannot dangle
}

pub struct LiveQuery {
    ditto: Arc<BoxedDitto>, // consider making Weak<BoxedDitto>
    pub query: char_p::Box,
    pub collection_name: char_p::Box,
    /// If created via `observe` contains the associated `Subscription` for the
    /// `LiveQuery`
    pub subscription: Option<Box<Subscription>>,
    /// An OWNED event handler, which is borrowed on the other side of the FFI.
    /// As such, `retain` and `release` methods for the handler can be None.
    pub event_handler: Pin<Box<dyn EventHandler>>,
    pub id: i64,
}

const UNASSIGNED_ID_SENTINEL: i64 = -1;

impl LiveQuery {
    #[rustfmt::skip]
    #[allow(clippy::too_many_arguments)]
    pub
    fn with_handler<F> (
        ditto: Arc<BoxedDitto>,
        query: char_p::Box,
        query_args: Option<Vec<u8>>,
        collection_name: char_p::Box,
        order_by: &'_ [COrderByParam], // Note COrderByParam is not opaque
        limit: i32,
        offset: u32,
        subscription: Option<Box<Subscription>>,
        event_handler: F,
    ) -> Result<Self, DittoError>
    where
        F : EventHandler,
    {
        let event_handler: Pin<Box<F>> = Box::pin(event_handler);
        let ctx = &*event_handler as *const F as *mut c_void;
        let mut this = LiveQuery {
            ditto,
            query,
            collection_name,
            subscription,
            event_handler,
            id: UNASSIGNED_ID_SENTINEL,
        };

        #[allow(improper_ctypes_definitions)] // false positive
        unsafe extern "C"
        fn c_cb<F : EventHandler> (ctx: *mut c_void, p: c_cb_params)
        {
            let ctx: *mut F = ctx.cast();
            let event_handler: &mut F = ctx.as_mut().expect("Got NULL");
            let event = if p.is_initial { // more explicit flag for "initial" status
                LiveQueryEvent::Initial
            } else {
                let moves: Vec<LiveQueryMove> =
                    p   .moves
                        .as_ref()
                        .unwrap()
                        .as_slice()
                        .chunks_exact(2)
                        .map(|it| if let [left, right] = *it {
                            LiveQueryMove::new(left, right)
                        } else { unreachable!() })
                        .collect()
                ;
                LiveQueryEvent::Update{
                    old_documents: p.old_documents.unwrap().into(),
                    insertions: p.insertions.unwrap().into(),
                    deletions: p.deletions.unwrap().into(),
                    updates: p.updates.unwrap().into(),
                    moves,
                }
            };
            event_handler(p.documents.into(), event);
        }

        let id = &mut this.id;
        let availability = LiveQueryAvailability::Always;

        *id = unsafe {
            ffi_sdk::ditto_live_query_register_str(
                &*this.ditto,
                this.collection_name.as_ref(),
                this.query.as_ref(),
                query_args.as_ref().map(|qa| (&qa[..]).into()),
                order_by.into(),
                limit,
                offset,
                availability,
                ctx,
                None,
                None,
                c_cb::<F>,
            ).ok_or(ErrorKind::InvalidInput)?
        };

        if *id == UNASSIGNED_ID_SENTINEL {
            ::log::error!("Live query was not given a valid id");
        } else {
            ::log::debug!("Live query id: {}", id);
        }

        // start the query
        unsafe {
            ffi_sdk::ditto_live_query_start(&*this.ditto, *id);
        }
        Ok(this)
    }
}

impl Drop for LiveQuery {
    fn drop(self: &'_ mut LiveQuery) {
        // Signals to the FFI that it can no longer borrow the live query's
        // event handler.
        ::log::debug!("Dropping LiveQuery {}", &self.id);
        unsafe { ffi_sdk::ditto_live_query_stop(&*self.ditto, self.id) };
    }
}

impl LiveQuery {
    pub fn stop(self: LiveQuery) {
        drop(self);
    }
}