Performance and param URL tweaks

sdk-lib/src/main/java/cash/z/ecc/android/sdk/ext/ZcashSdk.kt

@@ -37,19 +37,19 @@ object ZcashSdk {
     // Because blocks are buffered in memory upon download and storage into SQLite, there is an upper bound
     // above which OutOfMemoryError is thrown. Experimentally, this value is below 50 blocks.
     // Back of the envelope calculation says the maximum block size is ~100kb.
-    const val DOWNLOAD_BATCH_SIZE = 10
+    const val DOWNLOAD_BATCH_SIZE = 50
 
     /**
      * Default size of batches of blocks to scan via librustzcash. The smaller this number the more granular information
      * can be provided about scan state. Unfortunately, it may also lead to a lot of overhead during scanning.
      */
-    val SCAN_BATCH_SIZE = 150
+    val SCAN_BATCH_SIZE = 500
 
     /**
      * Default amount of time, in milliseconds, to poll for new blocks. Typically, this should be about half the average
      * block time.
      */
-    val POLL_INTERVAL = 20_000L
+    val POLL_INTERVAL = 38_000L
 
     /**
      * Estimate of the time between blocks.
@@ -87,11 +87,12 @@ object ZcashSdk {
     val OUTPUT_PARAM_FILE_NAME = "sapling-output.params"
 
     /**
-     * The Url that is used by default in zcashd.
+     * The Url that is used by default in hushd.
      * We'll want to make this externally configurable, rather than baking it into the SDK but
-     * this will do for now, since we're using a cloudfront URL that already redirects.
+     * this will do for now
      */
-    val CLOUD_PARAM_DIR_URL = "https://z.cash/downloads/"
+    val CLOUD_PARAM_DIR_URL = listOf("https://git.hush.is/hush/hush3/raw/branch/master/",
+        "https://github.com/hushmirror/hush3/raw/dev/")
 
     /**
      * The default memo to use when shielding transparent funds.

sdk-lib/src/main/java/cash/z/ecc/android/sdk/internal/SaplingParamTool.kt

@@ -57,7 +57,8 @@ class SaplingParamTool {
                 ZcashSdk.SPEND_PARAM_FILE_NAME,
                 ZcashSdk.OUTPUT_PARAM_FILE_NAME
             ).forEach { paramFileName ->
-                val url = "${ZcashSdk.CLOUD_PARAM_DIR_URL}/$paramFileName"
+                val url = "${ZcashSdk.CLOUD_PARAM_DIR_URL.random()}/$paramFileName"
+                twig("Downloading Sapling params from ${url}...")
                 val request = Request.Builder().url(url).build()
                 val response = withContext(Dispatchers.IO) { client.newCall(request).execute() }
                 if (response.isSuccessful) {