add shared-memory program (solana-labs#611)

* add shared-memory program

* add offset and reduce shared object size

Cargo.toml

@@ -3,6 +3,7 @@ members = [
   "utils/cgen",
   "utils/test-client",
   "memo/program",
+  "shared-memory/program",
   "themis/program_bn",
   "themis/program_ristretto",
   "token-lending/program",
@@ -12,6 +13,7 @@ members = [
   "token/program-v3",
 ]
 exclude = [
+  "shared-memory/client",
   "themis/client_bn",
   "themis/client_ristretto",
   "token/perf-monitor",

ci/script.sh

@@ -66,7 +66,8 @@ for Xargo_toml in $(git ls-files -- '*/Xargo.toml'); do
   _ ./do.sh dump "$program_dir"
 done
 
-# Run SPL Token's performance monitor
+# Run client tests
+_ cargo test --manifest-path=shared-memory/client/Cargo.toml -- --nocapture
 _ cargo test --manifest-path=token/perf-monitor/Cargo.toml -- --nocapture
 _ cargo test --manifest-path=themis/client_bn/Cargo.toml -- --nocapture
 _ cargo test --manifest-path=themis/client_ristretto/Cargo.toml -- --nocapture

docs/sidebars.js

@@ -6,6 +6,7 @@ module.exports = {
       "token",
       "token-swap",
       "memo",
+      "shared-memory",
     ],
   },
 };

docs/src/shared-memory.md

@@ -0,0 +1,32 @@
+---
+title: Shared memory Program
+---
+
+A simple program and highly optimized program that writes instruction data into
+the provided account's data
+
+## Background
+
+Solana's programming model and the definitions of the Solana terms used in this
+document are available at:
+
+- https://docs.solana.com/apps
+- https://docs.solana.com/terminology
+
+## Source
+
+The Shared memory Program's source is available on
+[github](https://github.com/solana-labs/solana-program-library)
+
+## Interface
+
+The Shared memory program expects one account and writes instruction data into
+the account's data.  The first 8 bytes of the instruction data contain the
+little-endian offset into the account data.  The rest of the instruction data is
+written into the account data starting at that offset.  
+
+## Operational overview
+
+This program is useful for returning data from cross-program invoked programs to
+the invoker.  Because the account does not need to be signed it is not reliable
+to use this program to pass data between programs from different transactions.

shared-memory/README.md

@@ -0,0 +1,6 @@
+# Shared memory program
+
+A shared-memory program on the Solana blockchain, usable for for sharing data
+between programs or within cross-program invocations.
+
+Full documentation is available at https://spl.solana.com