[KMP] Memory leak found in AnyAddress

[10gic]

Describe the bug
I found a memory leak in AnyAddress within the Kotlin package of Wallet Core.

dependencies {
    implementation "com.trustwallet:wallet-core-kotlin-android:4.1.7"
}

To Reproduce
The following code can trigger a memory leak:

    println("Test started")
    val publicKeyHex = "044ba28b11af1561042b03b9d0f940446315af11358aa12d798050b3cf76265dab0f48b22ea1fc1f9560c969b966221f2821b746c4e56efaeaeec8689caf5843c9"
    var i = 1
    while (i <= 1_000_000) {
        val publicKey = PublicKey(publicKeyHex.hexToByteArray(), PublicKeyType.SECP256k1Extended)
        val anyAddress = AnyAddress(publicKey, Ethereum, Derivation.Default)   // This leaks memory!
        if (i % 10_000 == 0) {
            println("Test case $i run")
        }
        i++
    }
    println("Test completed")

Expected behavior
No memory leak.

Screenshots
Memory Profiler Screenshot:

Additional context
The above test was conducted on Android. Based on the generated code in directory wallet-core-kotlin, this issue should also exist on iOS.

[satoshiotomakan]

Hi @10gic, good catch! I'll investigate what can be the reason for the memory leak.
Could you please advise if you caught the memory leak while using other WC bindings? For example, PrivateKey or HDWallet?

[10gic]

Hi @satoshiotomakan, I found that this is a common issue. It exists in HDWallet, PrivateKey, PublicKey, and others.

For swift binding (swift/Sources/Generated/AnyAddress.swift), we have deinit code to release memory:

    deinit {
        TWAnyAddressDelete(rawValue)
    }

For wasm binding (wasm/src/generated/AnyAddress.h), we have destructor to release memory:

    ~WasmAnyAddress() {
        TWAnyAddressDelete(instance);
    }

Kotlin don't support destructor, we need to think of other solutions to release memory.

[satoshiotomakan]

Hi @10gic, I see, thank you for the huge amount of work to find the root causes and propose the fix #4031, I'm checking it carefully right now.

[10gic]

Hi @satoshiotomakan, the pr #4031 only try to fix the issue #4030.

Issue #4030 and issue #4021 are two different types of memory leaks.

Issue #4021 hasn't been fixed yet.

[10gic]

Hi @satoshiotomakan, do you have any ideas on how to fix this issue (#4021)?

[satoshiotomakan]

@10gic
I scheduled a call this Friday with Kotlin engineers from another team. One of the ideas is to use native Swift, Java, JS wrappers to free the memory.
Unfortunately, I can't fully dedicate to the memory leaks as I'm currently focused on BTC PSBT, but will do the research and PR review end of this week