Add Golang SQLite demo

demos/golang/go_sqlite/.gitignore

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+simple_demo
+simple_demo_instance/

demos/golang/go_sqlite/README.md

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+# Use Golang and SQLite with Occlum
+
+This project demonstrates how Occlum enables [Golang](https://golang.org) programs with [SQLite](https://www.sqlite.org/index.html) library calls running in SGX enclaves. The way to use a SQL (or SQL-like) database in Go is through the [database/sql](https://golang.org/pkg/database/sql/) package. The SQL package exposes an ideal set of generic APIs for a variety of SQL or SQL-like databases. The SQL package itself must be used in conjunction with a [database driver](https://github.com/golang/go/wiki/SQLDrivers) package.
+
+The demo program is based on a widely used [sqlite3 driver](https://github.com/mattn/go-sqlite3) conforming to the built-in database/sql interface and passing the compatibility test suite at [https://github.com/bradfitz/go-sql-test](https://github.com/bradfitz/go-sql-test). You can run the Golang SQLite demo on Occlum via
+```
+./run_go_sqlite_demo.sh
+```
+
+The demo program adds a database source file golang_sql_driver.db, creates a table SqlDrivers, inserts a list of Golang SQL database driver records, queries all records, and prints them out.

demos/golang/go_sqlite/run_go_sqlite_demo.sh

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+#!/bin/bash
+set -e
+
+BLUE='\033[1;34m'
+NC='\033[0m'
+
+# Install SQLite with occlum-go
+occlum-go get -u -v github.com/mattn/go-sqlite3
+
+# Build the Golang SQLite demo program using the Occlum Golang toolchain (i.e., occlum-go)
+occlum-go build -o simple_demo simple_demo.go
+
+# Init Occlum Workspace
+rm -rf simple_demo_instance && mkdir simple_demo_instance
+cd simple_demo_instance
+occlum init
+new_json="$(jq '.resource_limits.user_space_size = "2560MB" |
+	.resource_limits.kernel_space_heap_size="320MB" |
+	.resource_limits.kernel_space_stack_size="10MB" |
+	.process.default_stack_size = "40MB" |
+	.process.default_heap_size = "320MB" |
+	.process.default_mmap_size = "960MB" ' Occlum.json)" && \
+echo "${new_json}" > Occlum.json
+
+# Copy program into Occlum Workspace and build
+cp ../simple_demo image/bin
+occlum build
+
+# Run the Golang SQLite demo
+echo -e "${BLUE}occlum run /bin/simple_demo${NC}"
+time occlum run /bin/simple_demo

demos/golang/go_sqlite/simple_demo.go

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+package main
+
+import (
+        "database/sql"
+        "fmt"
+        _ "github.com/mattn/go-sqlite3"
+        "os"
+        "time"
+)
+
+type GolangDbDriver struct {
+        dbName          string
+        pkgLink         string
+        testSuite       string
+}
+
+var DbDriverList = []GolangDbDriver {
+        GolangDbDriver {
+                dbName: "Apache Ignite/GridGain",
+                pkgLink: "https://github.com/amsokol/ignite-go-client",
+                testSuite: "Unknown",
+        },
+        GolangDbDriver {
+                dbName: "Amazon AWS Athena",
+                pkgLink: "https://github.com/uber/athenadriver",
+                testSuite: "Unknown",
+        },
+        GolangDbDriver {
+                dbName: "Google Cloud Spanner",
+                pkgLink: "https://github.com/rakyll/go-sql-driver-spanner",
+                testSuite: "Unknown",
+        },
+        GolangDbDriver {
+                dbName: "MS SQL Server (pure go)",
+                pkgLink: "https://github.com/denisenkom/go-mssqldb",
+                testSuite: "Unknown",
+        },
+        GolangDbDriver {
+                dbName: "MySQL",
+                pkgLink: "https://github.com/go-sql-driver/mysql/",
+                testSuite: "pass the compatibility test suite at https://github.com/bradfitz/go-sql-test",
+        },
+        GolangDbDriver {
+                dbName: "MySQL",
+                pkgLink: "https://github.com/siddontang/go-mysql/",
+                testSuite: "pass the compatibility test suite but are not currently included in it",
+        },
+        GolangDbDriver {
+                dbName: "Oracle (uses cgo)",
+                pkgLink: "https://github.com/mattn/go-oci8",
+                testSuite: "Unknown",
+        },
+        GolangDbDriver {
+                dbName: "Postgres (pure Go)",
+                pkgLink: "https://github.com/lib/pq",
+                testSuite: "pass the compatibility test suite at https://github.com/bradfitz/go-sql-test",
+        },
+        GolangDbDriver {
+                dbName: "Postgres (uses cgo)",
+                pkgLink: "https://github.com/jbarham/gopgsqldriver",
+                testSuite: "Unknown",
+        },
+        GolangDbDriver {
+                dbName: "Snowflake (pure Go)",
+                pkgLink: "https://github.com/snowflakedb/gosnowflake",
+                testSuite: "Unknown",
+        },
+        GolangDbDriver {
+                dbName: "SQLite (uses cgo)",
+                pkgLink: "https://github.com/mattn/go-sqlite3",
+                testSuite: "pass the compatibility test suite at https://github.com/bradfitz/go-sql-test",
+        },
+        GolangDbDriver {
+                dbName: "SQLite (uses cgo)",
+                pkgLink: "https://github.com/gwenn/gosqlite",
+                testSuite: "Unknown",
+        },
+        GolangDbDriver {
+                dbName: "Apache Hive",
+                pkgLink: "https://github.com/sql-machine-learning/gohive",
+                testSuite: "Unknown",
+        },
+}
+
+func main() {
+        previousTime := time.Now()
+        fmt.Printf("Starting the Golang SQLite demo: at %s\n", previousTime.Format("2006-01-02T15:04:05.999999999Z07:00"))
+
+        dbSourceName := "golang_sql_driver.db"
+        os.Remove(dbSourceName)
+
+        dbDriverName := "sqlite3"
+        db, err := sql.Open(dbDriverName, dbSourceName)
+        if err != nil {
+                fmt.Println("Failed to open the database:", err)
+        }
+        defer db.Close()
+
+        if err = db.Ping(); err != nil {
+                fmt.Println("Failed to establish a connection to the database:", err)
+        }
+
+        tx, err := db.Begin()
+        if err != nil {
+                fmt.Println("Failed to start a database transaction:", err)
+        }
+
+        sqlStatement := `
+        create table if not exists SqlDrivers (dbName varchar(255), pkgLink varchar(255), testSuite varchar(255));
+        delete from SqlDrivers;
+        `
+        _, err = db.Exec(sqlStatement)
+        if err != nil {
+                fmt.Println("Failed to create table:", sqlStatement, err)
+                return
+        }
+
+        statement, err := tx.Prepare("insert into SqlDrivers(dbName, pkgLink, testSuite) values(?, ?, ?)")
+        if err != nil {
+                fmt.Println("Failed to prepare SQL statements:", err)
+        }
+        defer statement.Close()
+        for _, entry := range DbDriverList {
+                _, err = statement.Exec(entry.dbName, entry.pkgLink, entry.testSuite)
+                if err != nil {
+                        fmt.Println("Failed to prepare SQL statements:", err)
+                }
+        }
+
+        tx.Commit()
+
+        rows, err := db.Query("select dbName, pkgLink, testSuite from SqlDrivers")
+        if err != nil {
+                fmt.Println("Failed to query the database:", err)
+        }
+        defer rows.Close()
+        for rows.Next() {
+                var dbName sql.NullString
+                var pkgLink sql.NullString
+                var testSuite sql.NullString
+                err = rows.Scan(&dbName, &pkgLink, &testSuite)
+                if err != nil {
+                        fmt.Println("Failed to Scan the query results:", err)
+                }
+                fmt.Printf("dbName=%v;\n  pkgLink=%v;\n  testSuite=%v\n", dbName.String, pkgLink.String, testSuite.String)
+        }
+        err = rows.Err()
+        if err != nil {
+                fmt.Println("Error was encountered during query result iteration:", err)
+        }
+
+        _, err = db.Exec("delete from SqlDrivers")
+        if err != nil {
+                fmt.Println("Failed to delete all records in the database:", err)
+        }
+
+        currentTime := time.Now()
+        fmt.Printf("Total running time: %f Seconds\n", currentTime.Sub(previousTime).Seconds())
+
+        os.Remove(dbSourceName)
+}
+