cr-sys 0.1.1

Rust raw bindings for cr.h: A Simple C Hot Reload Header-only Library
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

#include <stdint.h>
#include <stdio.h>
#include <stdbool.h>
#include <assert.h>
#include "../cr.h"

// To save states automatically from previous instance to a new loaded one, use CR_STATE flag on statics/globals.
// This will create a new data section in the binary for transferable states between instances that will be copied
// and kept around to overwrite the new instance initial states. That means that things that were initialized in
// a previous loaded states will continue from where they were.
static unsigned int CR_STATE version = 1;
// But unfortunately new added states in new instances (post the fact states) do not work because they will be
// overwritten by previous states (in this case, inexisting ones being zeroed), so uncommenting the following line
// will have a value of zero.
//static int32_t CR_STATE sad_state = 2;
// For this reason, cr is better for runtime modifing existing stuff than adding/removing new stuff.
// At the sime time, if we remove a state variable, the reload will safely fail with the error CR_STATE_INVALIDATED.
// A rollback will be effectued and this error can be dealt client side, for exemple, by poping a dialog box asking
// to force reload cleaning up states (restarting the client from scratch with the new version).

void hello() {
    // this demonstrate how to transfer an state between instances by using CR_STATE tag.
    // in this case, we track a flag to indicate if hello was print or not, so each new reload
    // after the initial one will not print the hello world message.
    static bool CR_STATE said_hello = false;
    if (!said_hello) {
        said_hello = true;
        fprintf(stdout, "hello world! ");
    }
    static int skip = 0;
    if (++skip%50 == 0)
	    fprintf(stdout, "y");
}

void test_crash() {
    int *addr = NULL; (void)addr; // warning
    // to test crash protection, uncomment the following line
    //int i = *addr;
}

CR_EXPORT int cr_main(struct cr_plugin *ctx, enum cr_op operation) {
    assert(ctx);
    if (operation != CR_STEP) {
        fprintf(stdout, "OP: %s(%d)\n", operation == CR_LOAD ? "LOAD" : "UNLOAD", ctx->version);
        int *addr = NULL; (void)addr; // warning
        // to test crash protection during load
        //int i = *addr;
        return 0;
    }

    // crash protection may cause the version to decrement. So we can test current version against one
    // tracked between instances with CR_STATE to signal that we're not running the most recent instance.
    if (ctx->version < version) {
        // a failure code is acessible in the `failure` variable from the `cr_plugin` context.
        // on windows this is the structured exception error code, for more info:
        //      https://msdn.microsoft.com/en-us/library/windows/desktop/ms679356(v=vs.85).aspx
        fprintf(stdout, "A rollback happened due to failure: %x!\n", ctx->failure);
    }
    version = ctx->version;

    // Not this does not carry state between instances (no CR_STATE), this means each time we load an instance
    // this value will be reset to its initial state (true), and then we can print the loaded instance version
    // one time only by instance version.
    static bool print_version = true;
    if (print_version) {
        fprintf(stdout, "loaded version: %d\n", ctx->version);

        // disable further printing for this instance only
        print_version = false;
    }
    hello();
    test_crash();
    //std::this_thread::sleep_for(std::chrono::milliseconds(500));
    return 0;
}